Albion made six changes to the team that drew at West Ham and started the match brightly against an Arsenal team off the back of a 3-1 victory against Chelsea on Boxing Day.
As so often this season though Brighton failed to convert good play and pressure into goals and sure enough Arsenal improved after the break and took their chance.
Bukayo Saka was impressive and it was his run and cross that teed-up second half substitute Lacazette who scored the winner with his first touch on 66 minutes.
Scroll down and click through to see how Graham Potter's players rated and who struggled.
1. Robert Sanchez 7/10
Once again a very confident display from the Spaniard and a super save in the second half to deny Aubameyang. No chance with the goal from Lacazette. Hard to see a way back for Maty Ryan
2. Adam Webster 6/10
Moved across to the right side of the defensive trio and solid in his defensive duties. Linked well at times with Veltman and tried to get Albion moving forward when he could
3. Lewis Dunk 6/10
Booked for a foul on the lively Smith-Rowe. Defended well, a threat at set pieces and did all he could to block Lacazette's goal
4. Dan Burn 6/10
Played left side of defensive trio and was exposed by Saka's pace as the Arsenal man expertly teed-up Lacazette's goal