Linz - US teen sensation Coco Gauff took full advantage of her lucky loser lifeline at the WTA tournament in Linz on Tuesday as she advanced to the second round.

The 15-year-old lost in qualifying to start the week but was inserted into the draw as a lucky loser after Greek Maria Sakkari quit before her first-round match with injury.

Number 110 Gauff, who got the spot as the highest-ranked loser from qualifying rounds, produced a 6-3, 7-6 (7/3) win over Swiss Stefanie Voegele.

"I had no expectations here, technically I had lost," she said. "I'm not looking past my next opponent.

"I want to keep playing my game and having fun - today was my lucky day and I hope to take that luck into the second round."

The celebrated youngster who beat Venus Williams in the Wimbledon first round and was consoled at the US Open by winning opponent Naomi Osaka after their third-round match, said her day in Linz had been hectic.

"We had gone back to the hotel after morning practice," she said. "We got the call and came straight back.

"I was on court 40 minutes later and didn't know much about my opponent. I got some info by word of mouth - but mostly it was me improving."

The victory was the first indoors at the WTA level for Gauff, already tipped as a major player for the future. She is competing in the fifth top-level tournament of her career.

"I live in Florida and we don't get indoors much. I enjoyed working on my game," she said.

Gauff needed to withstand a fightback from Voegele in the second set after the American won the first.

Gauff, who trained prior to this week for a few days at the Mouratoglou Academy in France, had to work to serve out the straight-sets win after leading 5-2 and ultimately needing a tiebreaker to move through.

"I'm satisfied, I saw improvement from yesterday (qualifying)," she said. "The indoor courts are faster, but I don't have to do much to adapt my game.

"It's not much different here than an outdoor hardcourt."

She praised Osaka for her kind treatment after their US Open clash. Osaka insisted that the defeated Gauff remain on court post-match and take part in an interview with her.

"In the moment I didn't want to do it," Gauff said. "I was trying to get out of it.

"But looking back, I'm glad she did that for me. It was good for the world to see.

"We both wanted to win, but when it's over, we don't hate each other.

"We don't like (opponents) when playing, but it's different when it's over. It's OK to be nice to your opponent.

"Sport is supposed to teach you things and teach the world everything."

Cori Gauff (USA) bt Stefanie Voegele (SUI) 6-3, 7-6 (7/3)

Alize Cornet (FRA) bt Barbora Strycova (CZE x7) 6-4, 6-4