Arsenal came from behind for the first time in a Premier League game this season to beat Southampton and move to within five points of the top four.
The Gunners saw their defence of the FA Cup end with a fourth-round defeat at St Mary’s on Saturday but they returned three days later to record a 3-1 victory.
Southampton looked on course to see off the visitors once more as Stuart Armstrong fired them ahead with a fine third-minute volley.
The win moves Mikel Arteta’s side above Southampton and up to eighth in the table, just five points behind London rivals West Ham – who occupy fourth place after a win at Crystal Palace earlier in the evening.
Arteta was still unable to call on captain Pierre-Emerick Aubameyang, who remains absent due to a personal matter, but he made five changes from Saturday as Saka and Lacazette scored on their recalls.
Lacazette should have opened the scoring inside 50 seconds but could not beat Alex McCarthy in the Southampton goal having been played in by Granit Xhaka.
The visitors did not allow their heads to drop and were level soon after, Pepe – who had let Armstrong run off him to score – made amends by collecting another good Xhaka pass and holding off his man to equalise.
With both sides looking to take the lead, Bernd Leno made a fine stop to keep out a Che Adams header.
It would be Arsenal who led at the break as Lacazette slipped a ball through to Saka, who rounded the onrushing McCarthy with ease and showed good composure to slot in his fifth of the season.
The win is a fifth from Arsenal’s last six Premier League games following the turnaround in form which started with a Boxing Day victory over Chelsea.
Arteta refused to be drawn on his ambitions for the season the last time he spoke to the media but, with high-flying Manchester United next up at the Emirates Stadium on Saturday, this win certainly means the Spaniard will continue to look up, rather than down.
Conversely, Southampton slip to 11th and have now won just one of their last seven in the league following their fine start to the campaign.