London - Three-time major winner Stan Wawrinka and girlfriend Donna Vekic defied the odds to make the Wimbledon second round Monday with the Swiss veteran describing it "as a good day at the office".
Wawrinka, 33, stunned Bulgarian sixth seed Grigor Dimitrov 1-6, 7-6 (7/3), 7-6 (7/5), 6-4 on Centre Court.
Just hours earlier on Court One, 22-year-old Vekic had shocked fourth seeded US Open champion Sloane Stephens 6-1, 6-3.
"I think it was a good day for us at the office, that's for sure," said Wawrinka, a former Australian Open, US Open and Roland Garros champion.
"It was great match from her. I watched it from home before coming back for my match.
"For sure it was a big win for her. She's playing well on grass. It's been good for us today."
Wawrinka, whose ranking has slumped to 225 after knee surgery, had lost his last four matches against Dimitrov, a semi-finalist in 2014.
But at the same tournament where he played what proved to be his last match of 2017, the 33-year-old was rejuvenated on Monday.
"It's a great feeling to win like this on Centre Court," added Wawrinka, twice a quarter-finalist at Wimbledon.
"I was moving well and feeling good.
"I knew it would be tough to beat a player like Grigor so my goal was to fight and focus."
Wawrinka will next face Italian qualifier Thomas Fabbiano.
Twelve months ago, Vekic was in tears after losing a second round thriller 10-8 in the final set to Britain's Johanna Konta.
But on Monday, she celebrated her first ever win over a top-five player.
"I finally got through a match like that," Vekic told the WTA.
"The last couple of times I played against top players I was playing good, but I would still lose. My team were always saying it's gonna come and I'm happy it was today."
As well as Konta last year, at Wimbledon in 2016 Vekic was drawn against another top 10 player in five-time champion Venus Williams.
"Playing Wimbledon is special, getting to play on Court One is even more special and I'm happy I've got some good memories out of it," said Vekic who now faces Sweden's Rebecca Peterson.
For 27-year-old Dimitrov, Monday was another setback after reaching only the second round at Queen's in the run-up to Wimbledon.
His defeat on Monday was the first time he had lost in the opening round at Wimbledon since 2009 which was also his debut year.
"I don't want to say it's unacceptable. Stan is an incredible player. I'm friends with him off the court," said Dimitrov.
"For sure, I wish him all the best that week. It's hard to come back after injuries, he's hungry, more determined, all that.
"But still it's hard for me to just accept losing, period. Especially at an event like this that I've done so well in the past. I've beaten big names on that Centre Court, played tough matches against big players.
"It's a tough pill to swallow."
Wimbledon results on Monday, the first day of the 2018 championships (x denotes seeded player):
Roger Federer (SUI x1) bt Dusan Lajovic (SRB) 6-1, 6-3, 6-4
Ivo Karlovic (CRO) bt Mikhail Youzhny (RUS) 4-6, 7-5, 7-6 (9/7), 6-3
Jan-Lennard Struff (GER) bt Leonardo Mayer (ARG x32) 3-6, 6-7 (5/7), 7-6 (7/5), 7-6 (7/5), 6-1
Adrian Mannarino (FRA x22) bt Christian Garin (CHI) 6-3, 1-6, 7-6 (7/4), 6-2
Ryan Harrison (USA) bt Roberto Carballes (ESP) 6-1, 6-4, 6-2
Guillermo Garcia-Lpez (ESP) bt Gasto Elias (POR) 6-2, 6-4, 6-2
Daniil Medvedev (RUS) bt Borna Coric (CRO x16) 7-6 (8/6), 6-2, 6-2
Sam Querrey (USA x11) bt Jordan Thompson (AUS) 6-2, 6-4, 6-3
Sergiy Stakhovsky (UKR) bt Joao Sousa (POR) 6-3, 6-3, 5-7, 1-6, 6-4
Gael Monfils (FRA) bt Richard Gasquet (FRA x23) 7-6 (8/6), 7-5, 6-4
Philipp Kohlschreiber (GER x25) bt Evgeny Donskoy (RUS) 6-2, 6-4, 7-5
Gilles Muller (LUX) bt Michael Mmoh (USA) 7-5, 4-6, 7-6 (9/7), 3-6, 6-1
Andreas Seppi (ITA) bt John-Patrick Smith (AUS) 6-2, 6-4, 6-1
Kevin Anderson (RSA x8) bt Norbert Gombos (SVK) 6-3, 6-4, 6-4
Marin Cilic (CRO x3) bt Yoshihito Nishioka (JPN) 6-1, 6-4, 6-4
Guido Pella (ARG) bt Jason Kubler (AUS) 6-4, 7-5, 4-6, 7-6 (7/3)
Mackenzie McDonald (USA) bt Ricardas Berankis (LTU) 4-6, 7-6 (8/6), 6-3, 7-6 (8/6)
Nicolas Jarry (CHI) bt Filip Krajinovic (SRB x28) 6-3, 3-6, 7-6 (7/5), 6-4
Lucas Pouille (FRA x17) bt Denis Kudla (USA) 6-3, 6-3, 2-6, 6-3
Dennis Novak (AUT) bt Peter Polansky (CAN) 6-2, 6-3, 7-6 (9/7)
John Millman (AUS) bt Stefano Travaglia (ITA) 6-7 (6/8), 6-3, 7-5, 6-2
Milos Raonic (CAN x13) bt Liam Broady (GBR) 7-5, 6-0, 6-1
John Isner (USA x9) bt Yannick Maden (GER) 6-2, 7-6 (7/4), 7-5
Stefanos Tsitsipas (GRE x31) bt Gregoire Barrere (FRA) 6-3, 6-4, 6-7 (3/7), 7-5
Jared Donaldson (USA) bt Malek Jaziri (TUN) 7-6 (7/5), 6-3, 6-1
Thomas Fabbiano (ITA) bt Yuki Bhambri (IND) 2-6, 6-3, 6-3, 6-2
Stan Wawrinka (SUI) bt Grigor Dimitrov (BUL x6) 1-6, 7-6 (7/3), 7-6 (7/5), 6-4
Karolina Pliskova (CZE x7) bt Harriet Dart (GBR) 7-6 (7/2), 2-6, 6-1
Victoria Azarenka (BLR) bt Ekaterina Alexandrova (RUS) 7-6 (7/4), 6-3
Katie Swan (GBR) bt Irina Camelia Begu (ROM) 6-2, 6-2
Kiki Bertens (NED x20) bt Barbora Stefkova (CZE) 6-3, 6-2
Anna Blinkova (RUS) bt Wang Yafan (CHN) 6-7 (4/7), 6-4, 6-4
Alexandra Dulgheru (ROM) bt Kristyna Pliskova (CZE) 6-4, 1-6, 6-2
Venus Williams (USA x9) bt Johanna Larsson (SWE) 6-7 (3/7), 6-2, 6-1
Lesia Tsurenko (UKR) bt Timea Babos (HUN) 7-5, 6-2
Andrea Petkovic (GER) bt Zhang Shuai (CHN x31) 6-4, 4-6, 6-2
Yanina Wickmayer (BEL) bt Mona Barthel (GER) 7-5, 6-4
Rebecca Peterson (SWE) bt Viktoria Kuzmova (SVK) 7-6 (7/3), 7-6 (11/9)
Donna Vekic (CRO) bt Sloane Stephens (USA x4) 6-1, 6-3
Kristina Mladenovic (FRA) bt Anna Karolina Schmiedlova (SVK) 5-7, 6-2, 6-2
Serena Williams (USA x25) bt Arantxa Rus (NED) 7-5, 6-3
Sorana Cirstea (ROM) bt Magdalena Rybarikova (SVK x19) 7-5, 6-3
Evgeniya Rodina (RUS) bt Antonia Lottner (GER) 3-6, 7-5, 6-4
Luksika Kumkhum (THA) bt Bernarda Pera (USA) 4-6, 6-2, 6-3
Madison Keys (USA x10) bt Ajla Tomljanovic (AUS) 6-4, 6-2
Madison Brengle (USA) bt Aleksandra Krunic (SRB) 2-6, 6-3, 6-3
Camila Giorgi (ITA) bt Anastasija Sevastova (LAT x21) 6-1, 2-6, 6-4
Ekaterina Makarova (RUS) bt Petra Martic (CRO) 7-6 (7/0), 2-6, 6-3
Caroline Wozniacki (DEN x2) bt Varvara Lepchenko (USA) 6-0, 6-3