Southampton moved further away from the relegation zone in the Premier League after a shock 2-0 win over Chelsea at Stamford Bridge on Boxing Day.
The Saints took the lead through Michael Obafemi in the first half before Nathan Redmond found the net for the visitors in the 72nd minute. Three unlikely points means Southampton moved up 14th after winning for the second time in as many matches, having beaten fellow strugglers Aston Villa 3-1 on Saturday.
Meanwhile, Chelsea stay fourth but are now just three points above fifth-place Tottenham Hotspur.
It took 21 minutes for either side to muster a shot on target, with Callum Hudson-Odoi going close for the home side. His effort didn't exactly help light the touch paper for the cagey hosts, who continued to disappoint in possession.
There was no shortage of application in midfield, thanks to the craft of Jorginho and N'Golo Kante's industry. Yet for all the running, Chelsea lacked efficiency with the final ball and didn't transition play quickly enough between the lines.
Chelsea's stuttering display was duly punished 10 minutes before the break when Saints made the most of their first attempt on target. It took a special finish from 19-year-old Obafemi, who was proving an able deputy for Danny Ings while Southampton's star man watched on from the bench:
Hudson-Odoi had been dispossessed in the build-up to the goal, and the raw winger was routinely losing out in one-on-one duels. His struggles were making the home supporters weary while also robbing Chelsea of a credible threat from wide areas.
Lampard reacted after the break by hooking centre-back Kurt Zouma for playmaker Mason Mount. The change nearly paid immediate dividends following the restart when Mount teed up Abraham, but the striker could only hit the side netting.
Chelsea's profligacy continued when Hudson-Odoi curled a shot on to the roof of the net from distance. The wayward strike continued what had turned into a torrid afternoon for the highly regarded 19-year-old.
A lack of tempo and composure on the ball were damaging the possession game Lampard prefers. Liam Twomey of The Athletic thought the absence of Mateo Kovacic was having a negative impact:
The schemer was serving a suspension, leaving Lampard to alter his team's shape rather than reshuffle the personnel:
Southampton weren't fazed, though, and might have had a second on the break, only for Kepa Arrizabalaga to deny Stuart Armstrong with a fine save. Saints obviously felt they would have more chances because top-scorer Ings came off the bench for Obafemi shortly after Lampard had finally withdrawn Hudson-Odoi for Christian Pulisic.
Southampton's confidence proved well-founded when Redmond put the away side two goals up with 18 minutes remaining.
The winger held his nerve after being played in at the end of a slick passing move and made no mistake with his finish:
Pulisic, skipper Cesar Azpilicueta and Mount went close for Chelsea late on, but the Blues ultimately failed to deliver after Sunday's impressive win away to Tottenham. Inconsistency continues to plague Lampard's team and could cost Chelsea a place in next season's UEFA Champions League.
Southampton face Crystal Palace at home in the Premier League on Saturday, while Chelsea are away to Arsenal for a London derby the following day.