Novak Djokovic is known as the best returner in the game, and he hit some memorable missiles with that shot in his 6-3, 7-6(5), 7-5 win over Tommy Haas in the quarterfinals on Wednesday. But this match was more notable for how dominant Djokovic was with his serve. He hit 11 aces and didn't double fault. He won 82 percent of his first serve points and 79 percent of his second serve points. Through the first two sets, he dropped just three points on serve and held at love seven times.

He was so dominant, in fact, that he made the match feel much more lop-sided than the score told us it was. Despite Djokovic's gaudy serving stats, he still had to scrape his way through a tense second-set tiebreaker to keep Haas from squaring things up. And that was no sure thing. Haas went up 4-2 in the breaker, only to give the lead, and essentially the match, away with three ugly errors. The worst of them was a putaway backhand volley that Haas popped long—instead of a 5-2 lead, he was back to 4-3. It was just one in a long series of botched forays forward for the German, who finished an unsightly 2 for 17 at the net. Otherwise, the 35-year-old Haas fought gamely in this match, made Djokovic work for each of the last two sets, defended well from way back in the court, and finally appeared to run out of gas in the last few games.

Djokovic played this one with what appeared to be a special determination and sense of purpose—he has vowed to win the tournament for his late coach, Jelena Gencic, who passed away last week. Today he began by gunning his returns and pressuring Haas in his opening service game, and he eventually broke him twice in the first set, each time by blitzing a forehand down the line for a winner. When Djokovic did falter later, he didn’t let himself slide for long. At 5-5 in the second-set tiebreaker, with the course of the match in the balance, he hit his best shot of the day, finishing a long rally with a cross-court backhand winner. In the third set, after twice losing his concentration and losing his serve, he calmed down right away and got back to grinding the older player down. Djokovic wasn’t flawless, but he was very good, even in the forecourt. He finished with 45 winners against 25 errors, and won 22 of 27 points at the net.

Haas’ run comes to an end, and with it go the last of the one-handed backhands from Paris. Djokovic moves on to a highly anticipated semifinal with Rafael Nadal. In one of his post-match interviews, the world No. 1, who has never won at Roland Garros, had already zeroed in on a key to that blockbuster: If he can serve like he did today...