After a slow start, and with a lot at stake, can Zverev flip a switch?

“The first of many more,” Alexander Zverev told Felix Auger-Aliassime after beating him 6-1, 6-4 in their second-round match in Monte Carlo on Wednesday.

Those were nice words. This had been a much-anticipated matchup of two young stars, and the 18-year-old Auger-Aliassime hadn’t been anywhere close to his best; he probably appreciated getting a confidence boost from the more-established player when it was over. And Zverev is right, he and Auger-Aliassime are likely going to be on tour together for the next 10 to 15 years, and their paths will cross dozens of times.

The question isn’t whether they’ll play each other in the future; the question is when they’ll play each other. Will it be in on Wednesdays, in early-round matches? Or will it be on Sundays, in Masters finals and for Grand Slam title? Zverev, obviously, thinks it’s going to be the latter.

Judging by what we’ve seen so far this year, it isn’t Auger-Aliassime’s future that we need to worry about—it’s Zverev’s. After winning his biggest career title at the ATP Finals in London last November, the 21-year-old German—he’ll turn 22 on Saturday—has stumbled out of the gate in 2019. He lost in straight sets to Milos Raonic in the fourth round of the Australian Open; he lost early in Indian Wells and Miami; his first foray onto clay, last week in Marrakech, resulted in another early defeat; and his one success, a trip to the Acapulco final, ended in a dispiritingly one-sided loss to Nick Kyrgios.

Yet so far Zverev has managed to hang on to his lofty No. 3 ranking. That’s because the lion’s share of his points from last season came during the clay-court swing. In 2018, he reached the Monte Carlo semifinals, won Munich and Madrid, reached the Rome final, and lasted until the quarters at the French Open. All of which means that crunch time has begun for Zverev in 2019. He obviously has a lot on the line over the next two months.

Is Zverev ready to flip the switch? We’ve seen him do it before. His career has tended to go in peaks and valleys, to alternate between two-or-three-month periods when he looks nearly unbeatable, and two-or-three-month periods when he looks highly beatable. Zverev himself remains sure his long-term prospects, and in general that’s a positive. But not always, according to one of his former coaches, Juan Carlos Ferrero, who said that the better Zverev became, the later he showed up for practice.

“The first months he was disciplined and respectful,” Ferrero said of their working relationship, which ended early last year. “But when he got more confident, he no longer respected the guidelines I marked out at the beginning.”

We can only assume that Zverev is more respectful of his current coach, Ivan Lendl, though their results together so far have been surprisingly up and down.

Wednesday, for the most part, was an up day for Zverev. He jumped out to an early lead over Auger-Aliassime, and he reminded us again of his unique ability to control rallies from well behind the baseline—to play aggressively, but with little risk. But Zverev also reminded us that he can struggle to put the clamps down on a match that would seem to be his for the taking. He let Auger-Aliassime go up a break in the second set before reeling off the last three games. Even then, it was Auger-Aliassime’s erratic backhand, rather than anything that Zverev did, that made the difference down the stretch.

Zverev may get a tougher, more ornery test from his next opponent, Fabio Fognini. You never know what you’re going to get from the veteran Italian, but he does seem to enjoy keeping the Next Gen players in their places whenever he can.

By next week, Zverev will be 22; even in this era of longevity, that’s an age that would seem to mean he’s entering his prime. Will he enter it on an upswing? Will his win today be the first of many more this clay season? If he wants to maintain his lofty ranking, he'll need all the wins he can get.