Jakub Mensik clinched Czechia’s victory against Norway at the United Cup on Monday, when he downed fellow Top 20 star Casper Ruud 7-5, 7-6(6) in Sydney.

Making his United Cup debut and playing his first match of the season, Mensik’s win followed Barbora Krejcikova’s victory against Malene Helgo to give Czechia a 2-0 win in the Group D tie, eliminating Norway, which fell to 0-2 this week.

Mensik held his nerve late in both sets, earning a crucial break at 5-5 in the opener before serving for a one-set advantage. Mensik later rebounded from failing to serve out the match at 5-4 in the second set. He trailed 3/5 in the second-set tie-break, yet won five of the next six points to survive. The winner of last year’s ATP Masters 1000 event in Miami, Mensik crushed a forehand pass cross-court when facing a set point at 5/6 in the second-set tie-break.

“First match of the season, it’s never easy,” Mensik said during his on-court interview. “It’s been a great fight. I’m grateful for the win. I managed in both sets to find the power at the end, that was the most important thing.”

At 20 years and four months, Mensik is the second-youngest man to record a singles win in United Cup history, behind an 18-year-old Stefanos Sakellaridis in 2023. The World No. 18 in the PIF ATP Rankings improved to 2-0 in his Lexus ATP Head2Head series with Ruud, whom Mensik beat at last year’s Australian Open in the second round.

Mensik crushed 16 aces and won 78 per cent of his first-serve points, according to Infosys ATP Stats, compared to Ruud’s 56 per cent.

Earlier, two-time major singles champion Krejcikova scored a winning United Cup debut in a 6-4, 6-3 triumph over Norway’s Helgo.

The former World No. 2 comes into the 2026 WTA Tour Driven by Mercedes-Benz season ranked No. 65 in the PIF WTA Rankings after another bout with injury to close 2025. She reached the quarter-finals of the US Open in September, a watershed moment in her season that only began in May after dealing with a recurring back injury.

Putting Team Czechia on the scoreboard 📋 pic.twitter.com/EihT4A8bFV

— United Cup (@UnitedCupTennis) January 5, 2026

Krejcikova then unfortunately dealt with physical problems again, suffering a knee injury against McCartney Kessler in the third round of the China Open. She retired from that match, later revealing her injury was worse than previously thought. Krejcikova also retired from her first match at the WTA 125 in Limoges in December.

Krejcikova’s season-opening match against World No. 532 Helgo proved to be an ideal return.

“I didn’t play for a long period, and the injury that I had was really tough and very unfortunate,” Krejcikova said. “I’m really happy that I’m here, that I can play, that I can enjoy it, that I can compete, and I’m really happy that I can finally finish a match.”

Helgo, 26, has punched above her weight in the United Cup in the past. She pushed both Caroline Garcia and Donna Vekic to three sets in 2024 and took advantage of a slow start by Krejcikova to open up an early 3-1 lead.

But then, Krejcikova, who played the one-hour, 38-minute match with supportive wrapping on her left knee, erased a break point opportunity in a five-deuce fifth game and righted the ship by winning eight of the next nine games.

“The knee is better. It took some time, but it’s improving every day and I’m very happy with that,” Krejcikova said.

Australia and Czechia are both 1-0 in Group D action. Mixed doubles between Czechia and Norway is up next at Ken Rosewall Arena.