Mohamed Salah, Liverpool Beat Manchester City to Advance to UCL Semi-Finals

Mohamed Salah and Roberto Firmino scored as Liverpool booked their place in the UEFA Champions League semi-finals for the first time since 2008 after beating Manchester City 2-1 on Tuesday night. 

The Reds won the second leg at the Etihad Stadium, despite falling behind to an early goal from Gabriel Jesus, to secure a 5-1 aggregate victory in the last eight.

There was an element of controversy, though, as referee Antonio Mateu Lahoz ruled out a second City goal for offside with Liverpool trailing 1-0 just before half-time.

Disallowed Goal the Wrong Decision and a Game-Changer

City had already set the tone by going ahead after one minute and 57 seconds. Yet it should have been 2-0 to the rampant hosts just before the break when Leroy Sane poked the ball home after a mix-up in the Liverpool defence.

However, the Germany international was ruled offside, although the decision was far from clear. In particular, the fact the ball rebounded off a Liverpool player, James Milner, should have meant the goal stood.

Former City striker Paul Dickov was incensed and hinted at his old club's recent misfortune with decisions, a possible reference to the Citizens being denied a clear penalty late on during Saturday's 3-2 loss to Manchester United in the Premier League:

Colin Millar of Football Espana was also far from impressed with Lahoz's decision and how it was interpreted during the match coverage:

In fairness, BT Sport host Gary Lineker agreed the ref got it wrong:

It didn't help City, though, particularly when manager Pep Guardiola was sent to the stands for the second half after some heated exchanges with the officials at the start of the break.

Guardiola already had issues with Lahoz, who made more than a few contentious decisions when the Citizens beat AS Monaco 5-3 in the first leg of the round of 16 last season, per James Ducker of the Daily Telegraph.

Lahoz continued to upset the City faithful, not only by disallowing a goal but also with the decision to not play a single second of stoppage time at the end of the half.

Goal's Sam Lee was bemused:

Chalking off Sane's finish took the air out of City. From the stands, to the dugout and onto the pitch, the erroneous decision changed the game as anger seemed to give way to resignation from the hosts, who believed it wasn't going to be their night.

Positional Switch Helped Salah Make History

An away goal didn't look likely after City's rapid start. However, when one eventually came, it was no surprise Salah provided it.

The prolific Egypt international's deft finish 11 minutes into the second half effectively killed the tie. It also meant Salah made club history in the competition, per OptaJoe:

Yet the landmark goal only came about thanks to a subtle but key switch of position for Liverpool's star man.

Jurgen Klopp moved his attacking talisman off the right wing, where he had been largely anonymous, into a central role. The move gave Salah more license to use his direct pace against Nicolas Otamendi and Fernandinho.

City's second goal also owed a lot to the change when Firmino, who had moved on to the left to make way for Salah's central switch, raced off the flank to score brilliantly.

Klopp deserved praise for how he helped turn the tide with a progressive, rather than pragmatic, change to put City on the back foot.

City's switch to 3-4-3 Gave Liverpool Early Problems

One of the key tactical tweaks Guardiola was counting on was the switch to a 3-4-3 formation. Stuart Brennan of the Manchester Evening News showed how City lined up in the altered structure:

The change moved the quicker Kyle Walker from full-back to centre-back. His pace was a good safeguard against Liverpool's swift front three.

City's biggest benefit came from moving forward Sane to left wing-back. He was able to double up with Aymeric Laporte on Salah, keeping Liverpool's danger man quiet for the opening 45 minutes.

It also meant Sane had more freedom to run at nervy young full-back Trent Alexander-Arnold. ESPN FC's Mark Ogden noticed how the 19-year-old struggled to cope early on:

Alexander-Arnold picked up a booking as the Reds failed to provide the overworked defender with sufficient cover. Sadly for City, Sane wasn't able to get at his prey often enough during the second half.

Guardiola's tactical gamble initially paid off, but Klopp's counter ultimately proved decisive.

Aguero's Status a Mystery

Since they needed three goals, the hosts' decision to leave star striker Sergio Aguero on the bench was baffling. His absence from the starting XI was a mystery since he had returned from injury to come on as a substitute in the derby defeat to United.

He may have been taken out by Ashley Young's heavy challenge which went unpunished at the weekend, but City's No. 10 still seemed like a lock to start with the Champions League campaign in the balance.

The fact Guardiola opted for Jesus, while not introducing Aguero until 10 minutes after Salah had scored, left BBC Sport's Simon Stone understandably searching for answers:

A 13-point lead with six games left means Stone's point about the domestic title is well-taken. It's one more reason why Aguero starting on the bench was a curious call from Guardiola.

What's Next?

Now it's up to City to recover from losing three in a row and seal the Premier League crown. It won't be easy with a visit to Wembley Stadium to take on in-form Tottenham Hotspur up next for Guardiola's wounded squad.

As for Liverpool, the Reds will now focus on staying healthy for the semi-final, knowing they boast the pace and flair to win Europe's biggest prize for a sixth time.