Dayana Yastremska defeated Ajla Tomljanovic 6-2, 2-6, 7-6(3) in a dramatic final at the Toyota Thailand Open in Hua Hin on Sunday, and when it was over Nick Kyrgios took to Twitter to call out the Ukrainian champion for calling for a medical timeout while trailing 5-2 in the deciding set.

“That medical was trash,” wrote Kyrgios.

With the 2019 Australian Open set to kick off Monday in Melbourne (Sunday night at 7 p.m. ET), SI’s tennis experts and writers Jon Wertheim Stanley Kay, Jamie Lisanti, Daniel Rapaport and Tristan Jung pick winners, discuss this year’s top storylines, highlight must-watch matches and more.

As the stars of the ATP tour and WTA are in the midst of their off-seasons, and with the busy holiday season already upon us, it’s easy to forget that the new tennis season is just a few weeks away—the first tournaments of the 2019 season actually begin in the last few days of 2018.

So where are all the biggest names in the game kicking off their 2019 campaigns?

PARIS — Novak Djokovic said he was proud of his “most amazing last five months” despite losing to Karen Khachanov in Sunday’s Paris Masters final ahead of his return to world number one.

The 14-time Grand Slam winner will replace long-time rival Rafael Nadal at the top of the rankings on Monday, capping an astonishing revival that began with a fourth Wimbledon title in July.

Serena Williams’ claims of sexism in the US Open final have been backed by the governing body of women’s tennis.

WTA chief executive Steve Simon said the umpire showed Williams a different level of tolerance of Saturday’s outbursts than if she had been a man.