Top-ranked Novak Djokovic beat unseeded American Taylor Fritz 6-4, 6-3 to reach the Paris Masters semifinals and remain on course for a record-extending sixth title at the tournament.
Djokovic is also vying for a record 37th Masters title. He is tied on 36 with fellow 20-time Grand Slam winner Rafael Nadal.
Djokovic, who next faces seventh-seeded Hubert Hurkacz of Poland, is playing in his first tournament since losing the U.S. Open final in straight sets to Daniil Medvedev in September.
"I felt good, considering that it was only second match back on the tour from almost two months of not playing a competitive match," said Djokovic, who had a walkover in the third round after Gael Monfils pulled out injured.
"I have to be satisfied, but also there are things that need to improve, and I know that."
He could face Medvedev, the defending Paris Masters champion, in the final again this Sunday. The second-seeded Russian saved three set points at 5-4 and 0-40 in the first set before beating French qualifier Hugo Gaston 7-6 (7), 6-4.
He next plays fourth-seeded Alexander Zverev, whom he beat in last year's final. Zverev was largely untroubled in a 7-5, 6-4 win against No. 6 Casper Ruud of Norway.
Zverev leads Medvedev 5-4 in career meetings, although Medvedev won the past three contests.
A double break of serve put Medvedev 4-0 up in the second set against Gaston.
But Gaston, who won seven straight games from 5-0 down in the second set against Spanish teen Carlos Alcaraz in the third round, rallied to 4-3.
Medvedev's 12th and 13th aces made it 5-3.
As they did against Alcaraz, the home crowd at times cheered Medvedev's errors on serve and they roared in delight when he double-faulted on his first match point. They were silenced when he clinched victory on his next attempt.
"It was a tough match, I have to say, in front of a very difficult crowd. ... Hugo played very well, he's very good," Medvedev said.
"He's able to put spin on the ball and to also have drop shots on the same ball. You never know what he's about to do, so it's not easy for your footwork."
Earlier, Hurkacz beat Australian James Duckworth 6-2, 6-7 (4), 7-5 to secure the last spot for the season-ending ATP Finals.
Following him onto court, Djokovic secured an early break for 2-0 but Fritz broke the Serb at love in the next game.
Djokovic had a love break of his own in the eighth game but slipped to 0-40 when serving for the first set after Fritz won a 26-shot rally, and then won the next point to pull back to 5-4.