Coco Gauff reached her first Grand Slam semi-final at the French Open on Tuesday when she defeated fellow American Sloane Stephens.

Gauff, 18 years old and ranked 23 in the world, triumphed 7-5, 6-2.

She will face Italy's 59th-ranked Martina Trevisan for a place in Saturday's championship match.

Victory avenged her defeat to Stephens at the US Open and helped erase the memory of her quarter-final defeat last year to eventual champion Barbora Krejcikova in Paris.

"I feel so happy," said Gauff. "Last year was a tough loss for me but I believe that match made me stronger.

"Last time I played Sloane I lost. Today was different. I stayed mentally strong as she is the kind of player who can make shots others can't do."

On Tuesday, Gauff broke in the second game of the match to lead 3-0 before 2018 runner-up Stephens levelled with a break and hold for 5-5.

However, clean, precise hitting allowed Gauff to dominate the 12th game to clinch the opener.

Stephens, playing in her first Slam quarter-final in three years, and Gauff traded breaks at the start of the second set before the teenager again pounced for 3-1.

Gauff held for 5-1, was broken for 5-2 before Stephens dropped serve for the fourth time in the set to hand her compatriot victory.

Gauff was junior champion at Roland Garros in 2018 and then burst into the public consciousness when just 15, she became the youngest woman to qualify for Wimbledon.

Her profile rocketed when she went all the way to the fourth round at the All England Club, knocking out Venus Williams on the way.

While in the French capital, Gauff has graduated high school, marking the occasion on Instagram with a family photo in front of the Eiffel Tower.

"Getting my diploma meant a lot to me," she said on Tuesday.

"Lots of players think tennis is the most important thing and it's not." (AFP)