It should hardly be a surprise when a player scores against their former club.
If a player leaves under good circumstances, then a positive reception from their former supporters, the experience of playing against the team in training, and even familiarity with their former stomping grounds can all factor into making their return a happy one for them and a miserable one for their old club.
If they've left under less amicable conditions, under a cloud, then in addition to these factors they have great motivation to make a point against their former employer, to make clear the error of their decision and to show them what they're missing.
There are a surprising number of ex-Liverpool players still in the Premier League this season. This could be seen as a good thing—some have found their level lower down the division, and the club has strengthened in their respective positions by replacing them.
However, it's hard not to see the departures of certain players to title-challenging sides either as evidence that Liverpool can't hold on to their best players like they once could, or that some mistakes have been made in the recent past.
The relatively short space of time in which Rafa Benitez, Roy Hodgson and now Kenny Dalglish have all sought to put their stamp on the club has resulted in some departures that may have been about bringing in "their" players in place of another manager's—justifiable but difficult when the departing players in question have shown promise.
Here are 10 former Reds who Dalglish will hope his newly assembled side can keep at bay.
This weekend Liverpool take on Stoke City, and could face up to three of their former players. Jermaine Pennant and Peter Crouch are likely to be integral to Tony Pulis' plans, while Salif Diao has settled in to a bit-player role at the club after some difficult years at Anfield.
Crouch has had a strange career. He has scored at a respectable rate of about one goal every three or four games in the last seven Premier League seasons, as well as at a relatively prolific one in two for England, but both Liverpool and Tottenham have been content to sell him and he's never truly established himself in the national side.
Stoke may be a smaller pond, but he'll relish the opportunity to prove his former clubs wrong and Liverpool will have to be wary of the threat he poses.
Meanwhile, Pennant has rehabilitated himself somewhat at Stoke, perhaps wiser now after indiscretions and inconsistency prevented him from living up to his potential at Arsenal and then Liverpool.
With Matthew Etherington on the opposite wing, Stoke have wide players who can deliver threatening balls into the box, although they have been at times overshadowed by Rory Delap's lethal throw-ins.
The two ex-Liverpool players might be at their most dangerous in combination—Pennant's crossing from wide on the right could find Crouch's head, although Liverpool fans will remember that despite his size, his heading and jumping technique isn't perfect.
Jose Enrique has had a strong start to his Liverpool career since joining from Newcastle and he'll need to be on top form to eliminate this threat. Jamie Carragher and Daniel Agger should have enough experience to deal with Crouch, but it won't be a comfortable afternoon for the Liverpool defenders.
Although the former Liverpool striker has fallen further and further down the pecking order at United since arriving there, Michael Owen has retained his eye for goal-scoring at a rate of about one goal every three appearances for United despite being largely used as a substitute. His mobility might not be what it was, but he remains a threat to Premier League defences when he appears.
Last season he picked up a Premier League winners medal (albeit by the skin of his teeth after numerous substitute appearances qualified him for the honour). His celebration afterwards and assertion that "if you can’t beat them, join them" didn't endear him to his past supporters.
With some dissatisfaction at the way he left Anfield for Real Madrid compounded by his move to Liverpool's greatest rivals, it's safe to say that fans would prefer not see the 31-year-old make a scoring return to Anfield.
Roy Hodgson has already delivered some payback for his dismissal by Liverpool last season, as his West Brom side defeated us 2-1 in April.
While West Bromwich Albion are a side that Kenny Dalglish will hope, nay, expect to beat, Hodgson has shown expertise in getting results with the league's less glamorous sides. The miracles he worked at Fulham, in the league and in Europe, were what secured him the Liverpool job in the first place.
When Liverpool face them this season, West Brom will be well-organised and difficult to beat as Hodgson seeks to exceed expectations once again. Unlike Michael Owen, he's also likely to get a good reception from Liverpool fans.
Although his tenure can only be regarded as a failure, there seems to be a feeling among many supporters that it was just a poor match between manager and club, with seemingly no ill will in either direction.
The previous owners drew some of the flak for his appointment (which was seen as unambitious, and a cheap option), and with their reputation so poor, Hodgson has emerged without much damage to his credibility.
Chelsea are well-stocked with ex-Liverpool players now, having signed Raul Meireles on deadline day. The Portuguese midfielder was well-liked at Anfield in his single season at the club, and although his transfer request may have soured that a little, he may not be the villain of the piece against the Blues.
Fernando Torres' departure last season seemed quite crushing for Liverpool when it took place, but thankfully Luis Suarez has already emerged as an exciting replacement. The Spaniard's move, which also funded the acquisition of Andy Carroll, is now seen as good business after just one goal in 20 games in a barren start to his Chelsea career.
Nevertheless, Torres is still an international striker who plays for the World Cup and European Championship holders, and he's a £50 million pound player—not someone to underestimate, especially when he has a point to prove.
Liverpool fans were disappointed by the lack of loyalty shown by their old No. 9 when Chelsea's interest became apparent, and alongside Meireles, he might expect at least a mixed reaction when he returns to Anfield.
Nicolas Anelka completes the trio of ex-Reds now plying their trade at Stamford Bridge. Although rumour has it that Andre Villas-Boas may be phasing him out of the Chelsea side (along with other members of the old guard there), with his years of experience at the top level throughout Europe, he's another striker that Carragher et al. will have to be wary of when the sides meet in November and again in May.
John Arne Riise makes his return to the Premier League with Fulham this season after three years at Roma, who he joined from Liverpool in 2008. He joins another ex-Red in Danny Murphy at Fulham, who at 34 is still playing and scoring for the Cottagers.
Riise is renowned for his powerful left foot. Liverpool fans will have to hope that Pepe Reina has an answer to the Norwegian's shots from range, or else that the returning Craig Bellamy's backswing is enough to put him off.
Until the arrival of Enrique this summer, Riise's position had arguably been left unfilled—Fabio Aurelio, Emiliano Insua and Paul Konchesky failed to match his fitness or consistency.
Still only 30, it seems strange that the hard working Scandinavian was allowed to leave the club. Although his occasional lapses in defence might provide opportunities for Liverpool in attack when they face Fulham in December and April, his attacking threat is rare from a left back.
David N'Gog never really established himself in the Liverpool side, but managed 19 goals at the club despite finding game minutes hard to come by.
At Bolton, he faces the tough task of replacing Johan Elmander, last season's top goalscorer, although he may face stiff competition for places from the experienced Kevin Davies and Croatian Ivan Klasnić, who has been in fine goal-scoring form at the start of the season.
Signed too late to play against Liverpool at Anfield, by the time the game at the Reebok rolls around in January, the 22-year-old will have to have proven that he's got more than just the potential he's shown over the last three seasons.
His pace and eye for goal would certainly indicate that he is Premier League standard, but he'll have to improve his composure and decision-making if he wants to make Kenny Dalglish rue his decision to sell.
Yossi Benayoun was a fan favourite in his time at Liverpool, chipping in with 29 goals from midfield in his three seasons at the club. However, Reds fans thought they had gotten the better of his move to Chelsea last summer, recouping his £5 million transfer fee when Joe Cole moved in the other direction in a free.
Despite Cole's failure to sparkle they may have been right. The Israeli succumbed to injury, playing just nine games for the Blues.
Undoubtedly though, Arsenal would appear to have gotten a good deal this time around. If Benayoun stays fit and displays his usual flair on the ball, he will fit right in to Arsenal's style of play and offer a credible replacement for the departed Samir Nasri.
He may only be on loan, but he'll be anxious to prove himself at one of the Premier League's biggest clubs after falling foul of managerial changes at Chelsea.
Liverpool face Arsenal again in March. A 2-0 win at the Emirates Stadium in August doesn't tell the full story, with numerous Arsenal players missing with injury and the club in turmoil during a difficult transfer window.
Yossi would certainly make the Gunners a different proposition in the spring if he featured.