Bernard Tomic and Thanasi Kokkinakis bowed out on day one of the US Open but hard-fought victories by Jordan Thompson and Ash Barty ensured Aussie fans had something to cheer about.

Thompson’s five-set win over 13th seed American Jack Sock was the standout performance, with the 23-year-old scrapping to victory in three hours and 56 minutes.

Tomic – playing his first match since admitting he was “bored” by tennis at Wimbledon – started brightly but was eventually beaten in four sets by Gilles Muller.

The 19th seed, who won 3-6 6-3 6-4 6-4, was a tough match-up for Tomic, given the Aussie’s current ranking of 146th.

Asked afterwards if he was motivated to play tennis again, Tomic said he was, but that he was not fully fit and he still felt “trapped” in the sport.

“It’s tough,” he said. “Everyone has their own work, their own job and it’s not like I can go and start real estate or something, restaurants. I’ve got no idea about that.

“Yes, I can afford to do those things, but I’ve got no idea. My job’s only to play tennis and it’s all I know.

“I’m not going to finish a doctor’s degree. I’m not the smartest person in the world.”

Tomic’s ranking will plummet further after his early loss, which means he may require a wildcard to compete at January’s Australian Open.

But Tomic said he would not ask for one – instead preferring to focus his energy on climbing up the rankings in future tournaments.

“It’s [low ranking] no sort of threat for me,” he said.

“I’ve been in this position before and I managed to turn it around quickly. It’s about being healthy the next six months to a year.”

Kokkinakis starts strongly but fades

Kokkinakis also faded after starting strongly, with Serbian veteran Janko Tipsarevic outlasting the Aussie to win 6-7 (5-7) 3-6 6-1 7-6 (7-2) 6-3.

Playing just his 13th ATP Tour match of an injury-interrupted year, Kokkinakis was made to pay for 64 unforced errors.

Thompson provided better news, though, surviving a scare to beat Jack Sock 6-2 7-6 (14-12) 1-6 5-7 6-4.

Thompson’s battle with Sock was one of the matches of the day. Photo: AAP

When Thompson won a marathon 71-minute second set, things were on his terms, only for Sock to dig deep and force an exciting finale.

Thompson held his nerve, though, making three breaks in a tense final set to claim victory.

The other Aussie male involved on Tuesday (AEST), was John Patrick Smith, who was beaten in four sets by Italian Thomas Fabbiano.

Barty fights back

All three of our girls posted victories, though, with Barty, who beat Venus Williams in the lead-up to the US Open, the most impressive.

Barty, now ranked 43rd in the world, came from a set down to topple 21st seed Ana Konjuh of Croatia, 4-6 6-0 6-1.

Arina Rodionova, who was Australia’s only player to reach the second round at Wimbledon, beat Richel Hogenkamp of the Netherlands, 7-5 7-5, while Ajla Tomljanovic also won in straight sets, toppling Sweden’s Johanna Larsson 7-5 6-4.

Elsewhere on an action-packed day one, Maria Sharapova, in her first grand slam match since her doping ban, beat second seed Simona Halep 6-4 4-6 6-3 in a thrilling encounter.