PARIS-Waking up early Friday for his third-round match at the French Open, Dominic Thiem was surprised to see that the morning skies were still dark. Yup, Roland Garros in autumn, when the sun is slower to rouse itself than during the usual May-June slot, takes some getting used to. But the U.S. Open champion is adjusting just fine to the peculiarities of what is now the last Grand Slam tournament in a pandemic-hit year.

The runner-up last year and in 2018, both times to Rafael Nadal, advanced to the fourth round for the fifth consecutive time, with another straight-set victory at Roland Garros in this year’s first encounter in Paris between seeded men. The victim of the third-seeded Austrian’s fierce backhand and super-quick court coverage under the new roof on Court Philippe Chatrier was No. 28 Casper Ruud, dispatched 6-4, 6-3, 6-1.

In the women’s draw, top-seeded Simona Halep defeated Amanda Anisimova 6-0, 6-1. The 19-year-old Anisimova had beaten the 2018 champion in straights set in the quarterfinals last year. Halep, a 29-year-old Romanian riding a career-best winning streak of 17 matches, will next face another rematch against another teenager: Iga Swiatek.

The 27-year-old Thiem, who is bidding to become the first Austrian with multiple Grand Slam titles, has said he loves the chilly autumnal conditions that other players have grumbled about at this year’s pushed-back French Open. Still, waking up in the players’ bio-secured hotel at 7 a.m. for the first match Friday on Chatrier, he was taken aback that dawn had to yet to break, as it would have done in May. “Everything dark. Winter is almost coming,” he said. “That was a little bit weird.”

Thiem was broken only once, when he sent a forehand wide to give Ruud a 3-1 lead in the first set. He immediately broke back and converted six of his 15 break points in all. He also saved seven of the eight break points he faced. Ruud was bidding to become only the second Norwegian to reach the fourth round of a Grand Slam. The first was his father and coach, Christian Ruud, at the Australian Open in 1997. He watched Friday on Chatrier.

Swiatek is a tougher prospect this year. She has lost only 13 games, not dropped a set and beat Canadian wild-card entry Eugenie Bouchard 6-3, 6-2 in the third round. Swiatek hit 30 winners and converted six of her 13 break points against the 2014 Wimbledon finalist now ranked 168th.