Chelsea manager Frank Lampard said his side "can only blame ourselves" after they let an early lead slip as Arsenal won the Heads Up FA Cup final.
Christian Pulisic scored an excellent opener but was injured before Pierre-Emerick Aubameyang's two goals secured the Gunners the trophy for a 14th time.
"We got complacent, took time on the ball like it was a stroll," Lampard told BBC One.
"We didn't play well enough to win a final. A lot of today is on us."
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Pulisic, 21, put the Blues ahead in a high-tempo start but captain Cesar Azpilicueta then gave away a penalty and pulled his hamstring.
At the start of the second half, Pulisic picked up a similar injury, before midfielder Mateo Kovacic was sent off for two bookings and substitute Pedro dislocated his shoulder at the end of a costly evening.
"We started well for 10-15 minutes and we can only blame ourselves from that point," he said.
"A final can never be a stroll and we allowed them back into the game.
"We were slow, we played back on ourselves, invited pressure."
Chelsea play Bayern Munich next weekend in the second leg of their delayed Champions League last-16 tie and Lampard could be struggling for players.
Lampard, who won the FA Cup four times as a player for Chelsea, said that midfielders Willian and N'Golo Kante were not fit to feature, and that Ruben Loftus-Cheek was also out of action.
"I'm not even thinking about next week," he said. "It all came together for us today - two hamstrings, a dislocated shoulder.
"It's the end of a long long season and it was the tipping point for us."