US Open: Naomi Osaka takes care of business against Elise Mertens while Iva Jovic edges out good friend Alex Eala in thriller

Naomi Osaka stepped on court in another new look and she eventually took care of business against Elise Mertens in a tense three-set victory to reach the fourth round of the US Open.

Osaka's 'business-chic' attire along with an all-out attacking game saw her come up clutch to land an impressive 6-3 3-6 7-5 win over 23rd seed Mertens on Louis Armstrong Stadium.

For her latest fashionable walk-on look, Osaka blended boardroom ​and locker-room aesthetics in a grey ‌checked blazer-hoodie and wide-leg pants, putting a tailored twist on traditional pre-match ​attire.

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"Honestly, I can't believe I won this match," Osaka said, thanking the crowd ‌for the energy they provided.

"There was a certain point where I put my heart on the court and kept trying in every point. Thank you so much, but ‌honestly, I'm shocked I won. I'm not going to lie."

The 28-year-old, a two-time champion at Flushing Meadows, reeled off three games in succession to take a 4-1 ​lead in the first set, ⁠clinching it with a battling hold thanks to a string of booming serves.

Osaka ‌pushed the Belgian hard at the start of the next set with some heavy hitting from the ‌baseline before pouncing with a break in the third game, only to surrender the lead by dropping the next two games.

Mertens levelled the match and forced a decider, where ⁠she capitalised on several unforced errors by ​a frustrated Osaka to gain the ​upper hand, but there would be another momentum ​shift in the match after a medical timeout for ⁠the Japanese player.

After recovering a break late on, Osaka fired a huge ace to take a 6-5 lead and ⁠revved up her forehand in ​the following game to earn ​a meeting with second seed Elena Rybakina or Yuliia Starodubtseva.

"I didn't play amazing ​and it was getting me down, sorry about my ​behaviour, for the little kids watching," said Osaka, who threw her racket ​to the floor at one point.

"This is my favourite tournament. I wanted ⁠to play well in front of you. I'm just that glad I have the opportunity to play another match.

"I thought I was going to be ok, but clearly I was ⁠shaky."

Jovic puts friendship with Eala on hold to win three-hour battle

Home hope Iva Jovic and ‌Alexandra Eala of the Philippines put their friendship aside for three hours before the 18-year-old American prevailed 7-5 3-6 7-5 on Arthur ​Ashe Stadium to reach the fourth round.

The two rising stars and close friends had already shared the ​court in New York during Fan Week when ‌they teamed up with their fathers for a light-hearted doubles hit.

Jovic edged a tight opening set but Eala responded in the second as the 21-year-old ​raising her level to force a decider.

The final ⁠set again featured momentum swings, with ⁠Jovic trailing 4-2 before fighting back to close out the victory and extend her head-to-head record ‌against Eala to 3-0, with a win on each of the three surfaces.

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"That felt like a marathon. I felt like I lost ‌my sanity five times over to win that match. But it's really worth it for this feeling," Jovic said on court.

"I'm usually not one that shows that many emotions. But this one really meant a ⁠lot to me. It's everything to have another ​match at the US Open."

Her victory sets up an all-American ​clash with Coco Gauff, who advanced earlier on Saturday by beating Spain's Cristina Bucsa.

The US Open is live on Sky Sports from August 30. Stream tennis with no contract on NOW and the Sky Sports App. You can also watch the Laver Cup at The O2 in London from 25-27 September live on Sky Sports.