Brighton salvaged a 1-1 draw against Chelsea thanks to a superb header from Danny Welbeck, who came off the bench.
Thomas Tuchel’s side struggled to get off to a good start, and they were dealt an early setback when Reece James walked off with an injury.
Lukaku wrestled past Neal Maupay and headed the ball past Robert Sanchez from a corner as the European champions gradually found their rhythm and took the lead.
After there, it was mostly one-way traffic, with the Seagulls forcing the issue due to the absence of injured Leandro Trossard.
Yves Bissouma forced two long-range saves from Edouard Mendy, while Maupay squandered two golden opportunities in the second half.
Welbeck headed home the equaliser from Marc Cucurella’s cross in the 91st minute to give Graham Potter’s team a deserved point.
The result ensures the Blues finish the season in second place in the Premier League table, ahead of Liverpool on Sunday, while Brighton climb to tenth.