A fine strike from Kai Havertz earned Chelsea a battling 2-1 victory at Red Bull Salzburg on Tuesday as they clinched a spot in the Champions League round of 16 as group winners.
Chelsea put on a dazzling display in the first half, taking the lead in the 23rd minute through Mateo Kovacic's instinctive left-foot finish from 20 metres, but they wasted several chances to double their advantage before the interval.
The Premier League side were made to pay for their profligacy early in the second half as Junior Adamu prodded home the equaliser, only for Havertz to restore Chelsea's lead with a superb curled strike into the top corner in the 64th minute.
Salzburg rallied late on but found keeper Kepa Arrizabalaga in fine form, helping the Blues to see out the win that moves them three points clear of second-placed AC Milan, whose 4-0 victory over Dinamo Zagreb meant Chelsea will finish top in Group E.
"It's not easy to create chances against this team but we did, we created good chances from good play," Chelsea coach Graham Potter said.
"We've had a lot of games and disruption in terms of key players missing but they (the team) have responded really well and to go through in the Champions League, it's a fantastic effort. We will take steps, tonight was one of those."
Despite Salzburg never having beaten English opposition in Europe, Chelsea's task coming into the match looked formidable with the Austrians on a 40-game unbeaten run in all competitions.
However, Kovacic's fine finish from the edge of the penalty area, after Havertz was dispossessed, settled the away team's nerves.
Chelsea should have capitalised further on their first-half domination but two superb saves from goalkeeper Philipp Kohn to thwart Gabon striker Pierre-Emerick Aubameyang, kept the hosts in the game.
Salzburg looked like a different team after the break, and levelled through Adamu three minutes into the second half, with the forward slotting home after a sweeping move.
The 2021 Champions League winners remained undeterred, with Jorginho's header cleared off the line before Havertz picked up Christian Pulisic's pass to settle the contest in style. It was his first goal from outside the penalty area for Chelsea.
Despite having to endure late Salzburg pressure, Chelsea deserved the win that continues their renaissance under new coach Potter.
The victory meant Potter became the second Englishman to go undefeated in his first nine games as Chelsea manager after William Lewis in 1906-07.
Salzburg are third in the group, and must beat Milan in Italy next week to reach the last 16.
"In the end the (team with) better quality have won," Kohn told Sky Austria. "Such a goal he (Havertz) doesn't score every day, I have to congratulate him for that. It's a little bit annoying, we would have liked to get a point."