Novak Djokovic edged out Holger Rune on Friday to avenge his defeat in last year's Paris Masters final and reach the last four, while Stefanos Tsitsipas set up a meeting with Grigor Dimitrov.
World number one Djokovic missed a match point in the second set but eventually claimed a 7-5, 6-7 (3/7), 6-4 win over Denmark's Rune in the quarter-finals after more than two-and-three-quarter hours on court at Bercy Arena.
The Serbian star is playing in his first ATP Tour event since lifting a record 24th Grand Slam title in New York in September.
Djokovic, the record six-time champion, will face either Alex de Minaur or Andrey Rublev on Saturday for a place in his ninth Paris Masters final.
The 36-year-old claimed his second career victory against Rune after suffering two successive defeats by the world number seven.
Djokovic snatched an opening set which was largely dominated by serve with a break in the 12th game.
He saw a match point come and go on the Rune serve when leading 5-4 in the second set, before the 20-year-old went on to produce a series of brilliant points in a tie-break to force a decider.
But Djokovic was clinical in the third set and a single break in the third game was enough to take him through.
Djokovic has now won 16 successive matches since losing to Carlos Alcaraz in the Wimbledon final.
He has won all eight of his previous Paris Masters semi-finals.
- Tsitsipas powers through -
Tsitsipas powered his way into the semis with a dominant 6-3, 6-4 victory over Karen Khachanov.
It was the 300th win of his career and gave the Greek, ranked sixth in the world, a semi-final match-up with Dimitrov who overcame Hubert Hurkacz 6-1, 4-6, 6-4.
Tsitsipas, who also reached the last four a year ago when he lost to Djokovic, has progressed to the same stage without dropping a set and produced an impressive variety of plays to counter Khachanov's baseline power.
"It's working well. I feel like I can mix up play," said Tsitsipas.
"It feels good to have so much variety and so much diversity in the way you can play."
Tsitsipas has already qualified for the end-of-season ATP Finals as one of the year's top eight players but defeat for Hurkacz against Dimitrov almost certainly rules the Pole out of contention.
Just two of the eight places for the event in Turin later this month are still open, with Alexander Zverev and Rune in pole position to clinch them. Hurkacz remains in a good position to be first reserve.
Dimitrov has no chance of reaching the ATP Finals but that did not prevent him from continuing his fine late-season form.
In the last few weeks, the 32-year-old Bulgarian has reached the semi-finals in Chengdu, a quarter-final in Beijing and the semi-finals of the Masters event in Shanghai.
His path to the last four of the Paris indoor event included a shock defeat of world number three Daniil Medvedev in the second round.
"My body is feeling well for now, that's the most important thing," said Dimitrov.
"My head is good. If I'm able to play like that on a consistent basis throughout every game, I put myself in a position to do better."
Dimitrov last reached the semi-finals in Paris in 2019 when he lost to Djokovic.