LONDON, Great Britain - Seven-time Wimbledon champion Serena Williams passed a tough test from talented teen Kaja Juvan at the All England Club, advancing 2-6, 6-2, 6-4 to reach the third round.

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Seeded No.11 at this year's Championships, the American caught fire after losing the opening set, and withstood a late surge from the 18-year-old Slovenian to ultimately advance after 94 minutes on No.1 Court.

"It was definitely coming together as the match went on," she said in her post-match press conference. "I'm just low on matches basically. I could feel it. But I'm getting there. Just have to, like I said, take every match as five matches, really learn from every single point."

Born at the start of the new millennium - and over a year after Williams won her first Grand Slam tournament at the 1999 US Open - Juvan won two gold medals at last year's Youth Olympic Games. She made her tour-level main draw debut three weeks ago at Roland Garros as a lucky loser, losing to 2009 quarterfinalist Sorana Cirstea in three tight sets. 

Qualifying for the Championships for the first time, the Slovenian youngster shocked Kristyna Pliskova for her first WTA main draw match win - having also made a WTA 125K semifinal in Bol - but made a quantum leap to start against the 23-time Grand Slam champion, winning the first three games.

Williams was playing just her second match since Roland Garros, where she fell in the third round to fellow American Sofia Kenin, and despite a solid win over Giulia Gatto-Monticone on Tuesday, struggled with her service rhythm as she made just half of her first serves and lost serve a second time to drop the opening set.

"I like the pressure. I would rather be in this position than any other, and sometimes I play best when I'm down. I'm just a fighter and never give up."

The comeback began in earnest at the start of the second, with the former World No.1 breaking in the first game and continuing to pressure the Juvan serve until she earned a 6-2 set to match the teenager's.

Things were much closer early in the decider, with Juvan saving a pair of break points to move ahead on serve, only for the American to start rolling from there, winning 16 of the next 19 points to get within one game of victory.

Juvan made a brave last stand; twice two points from defeat, she broke and held serve to close in on leveling the match with the help of some impressive shot-making.

Undaunted by the idea of a tense ending, the American shut the door in vintage style, holding serve at love to seal victory.

"I just have to remember that I'm best at closing matches, I'm good at it. I just have to keep the mind frame of where am I, what do I do mentally to close matches. I have to kind of just shut my eyes and get there. It's just experience and match play. In the past two years I haven't played a lot of matches. I'm just trying to kind of get that back."

In all, she struck 24 winners to 26 unforced errors - 11 of which came in the first set - and converted four of 10 break point opportunities. 

"I absolutely would not be here if I didn't love what I do. I work really hard at what I do every day."

Awaiting Williams in the third round is a rematch of the 2018 Wimbledon semifinal between her and German Julia Goerges, who eased past her second qualifier of the tournament with a straight-sets win over Varvara Flink. Goerges has never taken a set in four previous meetings, including two last year at SW19 and Roland Garros.