Mehdi Taremi's late overhead kick handed Porto a 1-0 win over the Blues in Tuesday's quarter-final second leg in Seville but Chelsea reached the last four 2-1 on aggregate.

Croatia midfielder Kovacic suffered a hamstring problem in training on Monday so was a late withdrawal from Chelsea's Porto showdown, and will also miss Saturday's Wembley battle with Manchester City.

N'Golo Kante stepped up to start as he moved past his own latest hamstring concern, producing a midfield masterclass to draw high praise from manager Tuchel.

"It was very sad to see Kova yesterday after 20 minutes in training ... He felt his hamstring, I was very sad for him, and also we don't have so many experienced players when it comes to the Champions League," Chelsea boss Tuchel said.

"I think he is for sure out for the game against City as well, so it's a big loss. So we did it also for him today.

"And it was clear we had to use N'Golo ... he's like two players."

Chelsea will now face either Real Madrid or Liverpool in their first Champions League semi-final since 2014.

The Blues always had the upper hand after last week's 2-0 victory thanks to goals from Mason Mount and Ben Chilwell.

Porto snatched a goal in second-half added time but never truly threatened to turn the tie on its head.

Tuchel knows Chelsea won no points for style in Seville but made no apologies for his players' hard graft that yielded major dividend.

"It was a day to hang in there, to show all the effort, intensity, all the team spirit that was needed. If you don't have the experience, if you have a young team, then it's the time to keep the momentum and be together," Tuchel added.

"There is nobody here to clap you for a tackle so a lot of hard work in secret was done, and that's why I'm very, very happy."

Australian Associated Press