Sam Querrey fighting and grinding his way back to winner's circle

The 2016 season did not begin elegantly for Sam Querrey.

After undergoing offseason surgery on his right knee, he wasn't ready to go in early January and withdrew from the tournament in Brisbane, Australia. A week later in Auckland, New Zealand, he saved five match points against Aljaz Bedene in the first round but lost to fellow American John Isner in the second. The Australian Open? Don't ask.

Querrey won the first two sets against Dusan Lajovic, but on the hottest day of the fortnight, he went down in a cramping mess and was forced to retire after four sets. It did not look like the 28-year-old from Southern California would run off and produce the best start of his professional career.

But earlier this month, he reached the semifinals in Memphis, pushing No. 7 Kei Nishikori to three sets, then ran the table at Delray Beach -- for his first title in 3½ years -- dispatching former US Open champion Juan Martin del Potro in the process.

In Acapulco, Mexico, Querrey beat Dudi Sela and then avenged his loss to Nishikori, demoralizing the 2014 US Open runner-up 6-4, 6-3. On Thursday, Querrey fought back from a set down to beat U.S. teenager Taylor Fritz. Next up: Dominic Thiem in the semifinals.

For Querrey, this ended a 0-4 run against Nishikori and, perhaps more significantly, his recent top-10 karma. Querrey had lost 20 of his past 22 matches against top-10 players, including nine straight.

"Pretty excited to raise the trophy at the end in Delray," Querrey told ESPN.com from Mexico. "I was pretty stoked."

There was a palpable note of excitement in his voice, one that has been sometimes lacking over the years. That's not the only thing that has been missing.

"Confidence is a massive component when you're dealing with athletes," his new coach, Craig Boynton, explained earlier. "In the sticking moments, Sam . . . "

Boynton paused a moment to think.

"Let me put this the best way I can," he continued. "Sam's being a lot more resilient and a lot more positive in looking forward. He's taking care of the task at hand more than worrying about the opportunity lost.

"What does it take to get confidence? Everybody has a different process."

Winning, of course, creates confidence. And according to Querrey, it's also the way you win.

"It was windy at Delray," he said. "No one played that well. A lot of matches I won by fighting and grinding through, winning some ugly sets and points. A lot of times that gives you confidence."

Credit Boynton, Isner's former coach who also works with 34th-ranked Steve Johnson. That gives him charge of the third- and fourth-ranked American men, behind No. 11 Isner and No. 23 Jack Sock.

"He's eager, he's motivated," Boyton said. "Sam has always had the tennis piece. It's been a matter of getting to the bottom of some of the issues that were sticking points. We're building bricks from the bottom up."

One product of confidence is aggressive play. Boyton and Querrey are focused on staying in that mode more consistently, particularly in the big moments.

"Especially," Querrey said, "on break points, deuce points and tiebreakers. It's about committing to the process of getting better, instead of focusing on just winning a match. I'm hoping that win or lose, it will eventually translate into positive results."

Last year, Querrey's right patella was wearing down, so he shut it down in October and opted for surgery. Bone was taken from his hip and used to rebuild his knee -- which he says is as good as new.

Querrey, 28, is the same age as top-ranked Novak Djokovic and No. 2 Andy Murray. In today's game, it has been a sweet spot for players like Stan Wawrinka, Tomas Berdych and David Ferrer, who played the best tennis of their lives on the way to 30 and beyond.

This is good news for Querrey, because this looks to be a time of transition for the American men. Isner turns 31 in April, and there is an emerging young crew making some noise. Three qualified for the 32-man field in Acapulco, and two of them won their first match. Ryan Harrison, 23, stunned No. 3 seed Marin Cilic, and 18-year-old Taylor Fritz knocked off No. 8 seed Jeremy Chardy. Fritz will likely be the youngest player in next week's ATP top 100.

Ask Querrey about his specific short-term goals and he quickly says he has none. Later, as the conversation progresses, a few present themselves. He would love to replicate 2010, his best season, when he won four titles on four surfaces, produced a 39-24 match record and finished No. 18 in the world. That was also his career-best season in the Grand Slams, reaching the fourth round at both Wimbledon and the US Open.

Since then, he has failed to equal that feat in his past 19 majors.