RIO DE JANEIRO: Clay king and world No. 3 Rafael Nadal thwarted a determined challenge Thursday from fellow Spaniard Pablo Carreno Busta to reach the quarter-finals of the ATP Rio Open.

Top seed Nadal, determined to kick-start his season on clay as he targets a 10th French Open crown at Roland Garros, won 7-5, 6-3 against 55th-ranked Carreno to advance to a Friday meeting with Uruguayan Pablo Cuevas, ranked 23.

Cuevas saw off Spaniard Albert Montanes 6-2, 6-2.

Fourteen-time Grand Slam champion Nadal missed three set points in the opener and had to dig deep as his rival fought tigerishly to keep pace with his decorated rival, who is bidding to retain the title he won in Rio 12 months ago.

“It was pretty humid and he is a tough young cookie. I am very happy to be through to the quarters,” said Nadal, 28.

“It was a tough match. I was glad to get the break back when he got to 3-2. At 5-4 I made a couple of mistakes. Then in the second set I was a bit tired from the first to begin with and sought to bring my serve through.

“At 3-2 I tried to get the break and it didn’t come off but the next one did. For me every win is important — and especially on clay.”

In the host city for next year’s Olympics, 2008 Beijing Olympic gold medal winner Nadal improved his record to 16-0 on Brazilian soil, having won titles at Costa do Sauipe in 2005, Sao Paulo in 2013 and Rio last year.

The left-hander has made a tentative start to this year after a slew of injury problems last season.

He lost in the first round in Doha and then at the Australian Open made a surprise exit against Tomas Berdych.

Japanese teen Nishioka reaches Delray quarterfinals

In Delray Beach, Florida, Japanese qualifier Yoshihito Nishioka booked his first ATP quarter-final on Thursday with a 6-1, 6-3 win over Marinko Matosevic at Delray Beach.

Nishioka, a 19-year-old left-hander, notched just his second tour-level win, converting five of his nine break opportunities in the 69-minute encounter.

“I’m so happy,” said Nishioka, ranked 154th in the world. “At the beginning I was so nervous, but I think he was nervous, too. I just tried to make every ball. Every shot, I was focused on it.”

Nishioka is the first teenager to reach the Delray Beach quarter-finals since Bernard Tomic in 2012.

He’ll face Australia’s Tomic for a place in the semifinals. Tomic, now 22, held on Thursday to beat eighth-seeded Serbian Viktor Troicki 6-3, 6-7 (2/7), 6-4.

Tomic withstood 13 aces from Troicki, who is his doubles partner this week, sealing the win in just under two hours.

“Today was very cold so it was tough for both of us,” said Tomic, who reached his fourth quarter-final of the season.

“It was good tennis. We both served pretty good. I was happy to win because it’s a tough match playing Viktor.”

American Donald Young continued his strong start to the season, reaching his third quarter-final of 2015 with a 6-3, 6-2 victory over Colombian Alejandro Gonzalez.