Jack Sock is having a career year, but is he playing too much tennis?

Right now, only one tennis player on the ATP World Tour has a singles and doubles ranking in the Top 20, and that’s Jack Sock.

It’s a well-earned mark of distinction: Since last year’s Summer Olympics—where he won the bronze medal with Steve Johnson in men’s doubles and the gold in mixed with Bethanie Mattek-Sands—until now, Sock has played in seven finals between singles and doubles, and led the U.S. to a runner-up finish at the Hopman Cup to start the season.

He’s established himself as a dual threat, but how much tennis is too much? And could all of that time on the court leave him in a less-than-ideal state for the year’s remaining Grand Slams?

Before this past weekend’s Davis Cup tie against Australia, Sock made the doubles final at the Miami Open with partner Nicholas Monroe. This came after reaching the singles quarterfinals there, where he lost to Rafael Nadal.

It was Sock’s fourth quarterfinal-or-better appearance at a Masters 1000 event, dating back to the last two of 2016. Before Miami, in Indian Wells, he made his first Masters 1000 semifinal, defeating Grigor Dimitrov and Kei Nishikori along the way.

The Sunshine Double could be considered a success for the American. But this is where the Davis Cup naysayers might be able to build upon their argument that changes need to be made in the competition. After playing the doubles final in Miami, Sock was soon on a plane to Australia to play in the quarterfinals the following weekend.

The Australian squad, led by Nick Kyrgios, was solid, but Sock was still the heavy favorite in the opening rubber against Jordan Thompson. Buoyed by the home crowd, Thompson came up with the upset. After John Isner lost to Kyrgios, it was up to the doubles team of Sock and Johnson to avoid the sweep. They put the U.S. back in contention with a five-set win over Sam Groth and John Peers.

However, Sock wasn't able to play the reverse singles match against Kyrgios, who defeated his replacement, Sam Querrey, in straight sets to lead Australia into the semifinals.

Of course, as the top American, Sock was nominated for the team. But in a manner of preservation, would this have been the time to pass up a tie? Not only did he play a tremendous amount of tennis in California and Florida, but he’s also the top seed at the US Men’s Clay Court Championship in Houston this week. Travel is a crucial element of life on the ATP World Tour, and that’s a lot of hopscotching Sock will have done in a three-week span.

It's worth noting that he won his first singles title in Houston in 2015 and reached the final there last year, so he knows what it takes to succeed at the tournament.

Shortly after his breakthrough in Texas in 2015, Sock reached his first round of 16 at a major, at the French Open. He possesses a game built for clay, with a powerful forehand that he hits with loads of topspin, a punishing first serve and strong kicker for a second, and a grind-it-out (if need be) mentality.

Sock could be considered a contender at Roland Garros this year. And the 2014 Wimbledon doubles champion isn’t bad on the grass, either. Of course, expectations will be high for him at the U.S. Open, too.

But how much will be left in the tank by the time those tournaments roll around? As he’s shown over the past several months, he has the capability to go deep in any event he enters. How he paces himself over the course of the year will be the determining factor in whether he’s ready to take that next step at the Grand Slam level.