Serena Williams' ex-coach, Rennae Stubbs, was left speechless by commentary during Anna Kalinskaya's Cincinnati Open match. The commentator brought up Kalinskaya's ex, Jannik Sinner, noting his recent practice with Emma Navarro and suggesting it might be on the Russian’s mind.Kalinskaya took on Peyton Stearns in the second round of the WTA 1000 event in Cincinnati after receiving a bye in the first round. The Russian won the first set 7-6, and the American forced a decider by winning the second 6-4.In the third set, while Kalinskaya led 1-0, commentator Darren Kilfara on the World Feed made surprising comments about Kalinskaya's ex, World No. 1 Jannik Sinner. He said:"(Anna) Kalinskaya ended her relationship with Jannik Sinner... I noticed the other day that Sinner was out hitting with Emma Navarro... Don't know if that means anything... Makes you raise an eyebrow... I wonder if that's on Kalinskaya's mind at all..."A video of the same was shared on X.Stubbs reacted to it, writing:"I have no words"Rennae Stubbs ♈️ @rennaestubbsLINK@awfulannouncing I have no wordsOn a separate post, she asked who the commentator was, and upon being informed, she wrote:"Do better Darren"Rennae Stubbs ♈️ @rennaestubbsLINK@MavisTennis @lildarkcage Do better DarrenFans also slammed the commentary, calling it "horrendous," "dumb," and "weird" among other things.Jannik Sinner and Anna Kalinskaya confirmed their relationship in May 2024, supporting each other during major tournaments, including public appearances and a memorable US Open kiss. However, the romance ended in May 2025, when Sinner confirmed he was single at the Italian Open.Jannik Sinner and Anna Kalinskaya are in good form at the 2025 Cincinnati Open Anna Kalinskaya at the Cincinnati Open 2025 - Source: GettyAnna Kalinskaya, seeded 28, has shown grit on the hard courts in Cincinnati. She opened her campaign by edging Peyton Stearns 7-6(4), 4-6, 6-1, then delivered a statement victory over No. 5 seed Amanda Anisimova, winning 7-5, 6-4.She next faces compatriot and 12th seed Ekaterina Alexandrova. Kalinskaya entered Cincinnati with a 16-15 season record and a career-high ranking of No. 11 achieved in October 2024. She also lifted the doubles crown at the Madrid Open alongside Sorana Cirstea.Jannik Sinner, Cincinnati’s defending champion, is cruising in form. He returned from a post-Wimbledon break to demolish Daniel Elahi Galan 6-1, 6-1 in just 59 minutes, his fastest win of 2025. He followed that with a hard-fought 6-2, 7-6(6) win over Gabriel Diallo, extending his incredible hard-court win streak to 22 matches. The World No. 1 next faces Adrian Mannarino.