Chelsea resumed their Premier League season with a comfortable win but Reece James went off early in the second half after picking up another injury on his return to action.
Kai Havertz gave Chelsea the lead from close range before Mason Mount added another before half-time with a great strike from just outside the box.
But there was concern when James, in his first league game back since suffering a knee ligament injury, went down with another problem and was forced off.
It took just 16 minutes for Havertz to give the Blues the lead as he slid in to poke home a lovely low ball across the face of the goal from Raheem Sterling on the right-hand side.
Mount made it two on 24 minutes, curling a fine effort into the bottom corner from the edge of the box after being teed up by Havertz and following some good work from Denis Zakaria on the on-loan midfielder’s Premier League debut.
Koulibaly headed just wide from Cesar Azplicueta’s cross in the second half, but Bournemouth improved after James’ exit, with Ryan Christie forcing keeper Kepa into a good stop at his near post before Dominic Solanke almost found the bottom corner with a header.
Chelsea: Kepa, James (Azpilicueta 52’), Silva, Koulibaly, Cucurella, Jorginho, Zakaria (Gallagher 81’), Pulisic (Aubameyang 81’), Mount, Sterling (Chalobah 87’), Havertz