Hyeon Chung won his first match since advancing to the Australian Open semi-finals, defeating lucky loser Cameron Norrie 3-6, 6-3, 6-1 at the Delray Beach Open on Monday afternoon in one hour, 41 minutes.

“It was a really tough match today because the wind was really strong,” Chung said. “However, I tried to stay calm. The guy played really well at the baseline so I was just trying to focus every point.”

Just a year ago, Chung lost in Delray Beach qualifying. But after soaring from No. 104 to 58th in the ATP Rankings in 2017 — and also winning the inaugural Next Gen ATP Finals in Milan — the South Korean has quickly become a star on the ATP World Tour. The 21-year-old is now World No. 30.

“I’m trying to enjoy it all the time, because it’s my second time in Delray Beach,” Chung said. “I’m already better than last year.”

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Chung will face the winner of an all-qualifier match between #NextGenATP Kazakh Alexander Bublik and Franko Skugor.

American Donald Young also got off to a strong start in Delray Beach, ousting qualifier Ramkumar Ramanathan 6-1, 6-2 in 69 minutes for his first win of the season. The left-hander will play inaugural New York Open champion Kevin Anderson or Evgeny Donskoy in the second round.

Top seed Jack Sock will be in action Monday evening, as the American plays qualifier John-Patrick Smith in the final match of the day. 

No. 1 Roger Federer, +1
Five years and 106 days since his last reign at the top of the ATP Rankings, Roger Federer is back at No. 1 after winning his 97^th tour-level title at the ABN AMRO World Tennis Tournament in Rotterdam (d. Dimitrov). Read & Watch Final Highlights

The 36-year-old Swiss starts his 303^rd week at No. 1, more than 14 years after first rising to the top spot on 2 February, 2004. He is guaranteed to remain atop the ATP Rankings until at least 18 March. He and Rafael Nadal will resume their tussle for the top spot at the BNP Paribas Open in Indian Wells, the first ATP World Tour Masters 1000 tournament of the year, which begins on 8 March.

Federer’s return to No. 1 means Nadal slips to No. 2 in the ATP Rankings, while Rotterdam runner-up, Grigor Dimitrov, bumps Alexander Zverev out of the Top 4. Marin Cilic remains at No. 3.

No. 9 Kevin Anderson, +2
Kevin Anderson captured his fourth ATP World Tour title at the inaugural New York Open – beating Kei Nishikori and Sam Querrey in third set tie-breaks in the semi-finals and final – and is rewarded with a return to the Top 10 at No. 9. Read Final Report

READ: Anderson Focuses On Continuing His Climb

No. 31 Andrey Rublev, +3
Next Gen ATP star Andrey Rublev inched towards a Top 30 breakthrough, rising to No. 31 after reaching the Rotterdam quarter-finals (l. to Dimitrov). The 20-year-old Russian, who was runner-up at the Next Gen ATP Finals in Milan (l. to Chung), has made a strong start to the 2018 season. He reached the quarter-finals in Montpellier one week earlier (l. to Tsonga).

No. 43 Aljaz Bedene, +8
Aljaz Bedene is celebrating a new career-high of No. 43 after rising eight places in the ATP Rankings following his runner-up showing in Buenos Aires (l. to Thiem). It was the 28-year-old Slovenian’s third final appearance on the ATP World Tour.

READ: Ruthless Thiem Streaks To Buenos Aires Title

No. 50 Daniil Medvedev, +7; No. 59 Andreas Seppi, +22
Elsewhere, Daniil Medvedev returned to the Top 50 after a quarter-final run in Rotterdam, while former Top 20 star, Andreas Seppi, surged 22 spots to reclaim a place in the Top 60 (No. 59) after upsetting Zverev en route to the Rotterdam semi-finals (l. to Federer). The Italian is on the rise in the ATP Rankings this season, winning the Canberra Challenger title and making the fourth round of the Australian Open to claw his way back up from a position of No. 86 at the start of the season.