Top seed Novak Djokovic had to dig deep to reach the Wimbledon third round with a 6-4, 6-3, 6-7 (5/7), 7-6 (7/5) victory over Czech veteran Radek Stepanek on Wednesday.
Djokovic had dropped just five games in a ruthless first round demolition of Andrey Golubev, but the 2011 Wimbledon champion was pushed far harder by the canny Stepanek on Centre Court.
The 27-year-old Serb, beaten by Andy Murray in last year's final, surrendered a set for the first time in the tournament after squandering a 5-2 lead in the third set tie-break.
But he recovered his composure to finish off the 35-year-old, who has now lost 11 of their 12 meetings, in three hours and 17 minutes and will face French world number 44 Gilles Simon for a place in the last 16.
"I should have closed it out in the third set. I had some break point chances and the lead in the tie-break, so I should not have complicated my life in this way, but credit to him," Djokovic said.
"He is an entertainer and loves to engage the crowd. He is 35 but moves really well. Grass is his preferred surface and he was reading my passing shots."
Djokovic's victory ensured the world number two avoided the fate that befell his coach Boris Becker in 1987 when the German became the only male top seed to lose in the Wimbledon second round.
But while he was relieved to have reached the last 32, the six-time Grand Slam winner will have to raise his game significantly from this erratic effort if he is to add another major title to his glittering CV.
Djokovic has won just one Grand Slam in the last two years and has lost in five of his last six major finals, including an agonising French Open defeat to Rafael Nadal earlier this month.
Yet he hadn't lost to a player ranked as low as Stepanek since 2010 and it should have been plain sailing after a routine first two sets.
But Stepanek beat Murray at Queen's Club two weeks ago and proved a real menace to Djokovic as well.
After opting out of the Wimbledon warm-up events, Djokovic claimed his lack of time on the grasscourts had played a role in his sloppy display.
He also credited his close friend Stepanek for an impressive display and greeted him with a warm hug at the net once he had finally seen off the tenacious Czech.
"We are friends off the court, we practice a lot and we practiced just before Wimbledon so we know each others game well," Djokovic added.
"I came to Wimbledon without any match play and my first round match went quickly so I didn't have much time on grass.
"All in all it was a difficult one, but I'm glad I stayed in the match mentally and managed to win it."