The deal is subject to regulatory approval.
The result lifted Chelsea to third in the table and ended Brighton’s unbeaten start to the season.
Kaoru Mitoma and Tariq Lamptey were both on target in the second half as Arsenal were knocked out of the English League Cup in the third round.
Newcastle United have completed the signing of Alexander Isak from Real Sociedad for a club-record fee reported to be £60 million ($71 million).
“The World Cup is every footballer’s dream. I think I’ve got a bit of energy left in me to prove myself once again.”
