Then he refocused and turned it around.
Pospisil rallied for a 6-4, 3-6, 2-6, 6-3, 8-6 win over Britain's James Ward at the All England Club, advancing to the fourth round of a grand slam tournament for the first time in his career.
"I think I just kind of went all in and went for it mentally," Pospisil said of his ability to come back from a 2-1 deficit. "I did a really good job to raise the intensity and the energy.
"I lost my balance a little bit in the second and third sets. When your back's against the wall in the fourth set, if you lose that set it's over."
The Vancouver native fired 19 aces and had 57 winners en route to victory.
He struggled with his serve in the second and third sets before finding his groove again in the fourth.
"I was not serving well at all throughout the match then I found my rhythm again and started serving really well and picking my spots again," Pospisil said. "That was key."
The crowd threw its support behind the hometown favourite Ward from the begining, and Pospisil said he could feel the momentum swing in his opponent's favour because of it.
But it didn't affect the 25-year-old's performance.
"In terms of the crowd that's something you've got to be prepared for," Pospisil said. "If you're prepared for that mentally before the match then it won't surprise you. I've had a lot of experience playing in front of crowds like that with the Davis Cup, and I always seem to play well even if the whole crowd is against me so I wasn't nervous about that."
Pospisil, who won the Wimbledon doubles title with American Jack Sock last year, will next play Viktor Troicki.
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