Naomi Osaka falls at first hurdle in Abu Dhabi after Danielle Collins defeat
Osaka returned last month from a 15-month absence from the tour, during which she gave birth to her first child Shai, but has been handed some tricky draws and has lost three of her four matches so far this campaign.
Despite a close opening set that witnessed supreme serving from both players, Osaka struggled in her service games in the second set and failed to convert any of her six break point opportunities to fall to the American qualifier in one hour and 23 minutes.
"I know she's still only a couple of matches into her comeback. But I think she's playing well," said Collins, who is currently ranked 71 in the world.
"She played a good first set and was serving very well and doing some really great things out on court. I'm sure at this point it's just kind of regaining confidence and getting more matches under her belt and getting back into the routine of tournaments and that stuff, which can be challenging. But I thought she played well overall."
Japan's Osaka won her first three meetings with Collins but had lost their most recent affair coming into Abu Dhabi, a straight-sets defeat to the American in the first round of the 2022 US Open.
In windy conditions in the UAE capital, neither player was troubled on serve early on, with the first deuce of the contest coming in the 10th game as Collins served to stay in the set but the American shook off the pressure to hold for 5-5.
Collins created the first break point opportunity of the match in game 11 and converted her second chance to inch ahead 6-5.
Despite hitting a couple of double faults, Collins managed to close out the frame on her fourth set point to take the lead in 54 minutes.
Next up Rybakina
Each player dropped just two points behind their first serve in the opening set but it was Collins who capitalised on her chances, and with the wind in her sails, the former Australian Open finalist soon went up a triple-break 5-0 against Osaka in the second set.
Osaka tried to narrow the deficit but Collins played flawlessly on the break points, saving all six she faced on her way to a second-round meeting with the top-seeded Elena Rybakina.
Osaka is due back on court in Abu Dhabi later on Tuesday to team up with Tunisian Ons Jabeur in doubles against Chinese duo Zheng Saisai and Wang Xinyu.
Collins has announced this will be her final season on tour and has herself navigated some brutal draws in her first five weeks of 2024.
At the Australian Open, she beat three-time major winner Angelique Kerber before falling to world number one Iga Swiatek in round two.
She has been handed two more grand slam champions in Abu Dhabi in the form of Osaka and 2022 Wimbledon winner Rybakina.
Collins said wanting to live a normal life away from the constant travel and the daily grind on tour has been the main reason behind her decision to retire at the end of this season.
"At this point I feel like I'm ready for the next chapter and I'm really excited about it. I needed to have an end date and it gives my family and friends the ability to come support me in some final tournaments. I think that will be really special,” said the player from Florida.