Budding tennis stars collide in the 2019 French Open quarterfinals Thursday when American Madison Keys, 24, takes on Australian Ashleigh Barty, 23, in a match delayed one day by rain. The match begins at 6 a.m. ET from Roland Garros. Keys, who's gunning for her first Grand Slam title, was brilliant last time out as she broke Katerina Siniakova five times in a 6-2, 6-4 win. No. 8 seed Barty needed three sets to get past Sofia Kenin but is seeded six spots higher than Keys and won their most recent matchup, in February, in straight sets. Barty is the only woman to reach the quarterfinals of both majors this year. Sportsbooks list Barty as a -178 favorite (risk $178 to return $100), with Keys getting +150 (risk $100 to return $150) as the underdog in the latest Keys vs. Barty odds. Barty is favored by 2.5 on the "game spread," and the over-under for total games is 23. Before you make any Keys vs. Barty picks or 2019 French Open predictions, see what Gavin Mair picked.

Mair is the international women's tennis expert who called Naomi Osaka's U.S. Open championship at 32-1. Over the past two years, Mair is up an astounding 213 units on his tennis futures picks. If you had placed $100 on each of those picks, you'd be up $21,300.

Now Mair has broken down Keys vs. Barty from every angle and released an extremely strong pick. He's sharing it over at SportsLine.

Mair knows that in the 2017 French Open, Keys cruised to a 6-3, 6-2 win over Barty. But in the rematch this February, it was Barty who dominated, winning the Fed Cup match 6-4, 6-1.

"Keys has arguably the most firepower of any player on tour with perhaps the exception of Serena Williams," Mair told SportsLine. "She dictates with power strikes from the back of the court and tries to end points within a couple of rallies.

"On paper, Barty can be a difficult matchup for Keys in that Barty adopts a playing style with great variety, using slices to change the pace and height of the ball as well as taking advantage of the court dynamics by regularly approaching the net.

"Barty's favoritism is justified by the fact that she is the higher-ranked player and that when Barty played Keys earlier in the season -- on an indoor court in Asheville, N.C. -- she destroyed the American very easily," Mair continued. "In that match, Barty won 12 of the final 14 games and coaxed a whopping 31 errors from Keys' racket.

"However, Barty is very happy playing on an indoor surface but has yet to show she is a top-level player on clay," he added.

Neither player has faced an especially difficult draw, so there is a ton of mystery surrounding this match.

During his exhaustive analysis, Mair isolated a critical X-factor that made him jump all over one side of this must-see quarterfinal. He's sharing it, along with his exclusive best bet, over at SportsLine.

So who wins Madison Keys vs. Ashleigh Barty? And which critical X-factor makes one side of the match a must-back? Visit SportsLine now to see Gavin Mair's best bet for Keys vs. Barty, all from the famed expert who called Naomi Osaka winning the U.S. Open at 32-1.