Italian Sinner on the fast track in Paris

By Julien Pretot

PARIS (Reuters) - Italian rising star Jannik Sinner says he is still learning, but his performances on his French Open debut show that the 19-year-old is learning fast.

Sinner barged into the last 16 at Roland Garros with a solid 6-3 7-5 7-5 victory against Argentine Federico Coria on Friday for his best performance at a Grand Slam two years after turning professional.

The winner of last year's NextGen ATP Finals relied on his massive forehand to claim his third victory in straight sets, a feat that actually worried him a little.

"It's not about winning in straight sets or winning in five sets, obviously it's better to win in three sets, but I have to improve even my performance after three sets, for sure," said Sinner.

"Like in the U.S. Open, I lost in five sets, so I still have to learn very much about playing Grand Slams. I played one Grand Slam in U.S. Open, Australian Open, this is my third main draw, so I'm still young, I can improve everything."

A player often looking for a quick winner, Sinner is learning to be patient at Roland Garros, where the chilly and damp conditions are slowing the play.

But he has already made some great strides since last year.

"I remember one match in a Challenger tournament last year in Ostrava and I was playing the final, it was maybe a little bit colder, but it was raining, the court was very heavy and I lost 6-1 6-0," he said.

"So I think I have improved on something for sure, there's no question about that. But you can still improve everything. I mean especially when you're young like me."

On court 14 on Friday, Sinner was possibly his worst opponent, allowing Coria to stay in the mix due to unforced errors as he grew frustrated at times.

"That's also where I need to improve, I need to stay a little bit calmer otherwise I lose some mental energy," he said.

Sinner's pace and poise, however, helped him recover from being down a break in the third set to wrap up a straightforward win.

Sinner will play his first fourth round match at a Grand Slam against German sixth seed Alexander Zverev, who beat another Italian, Marco Cecchinato, 6-1 7-5 6-3 on Friday.

(Reporting by Julien Pretot; Editing by Christian Radnedge)