World number one Maria Sharapova was forced to dig deep before securing her place in the Wimbledon third round with a 7-6 (7/3), 6-7 (3/7), 6-0 victory over Bulgaria's Tsvetana Pironkova on Thursday.
Sharapova had crushed Anastasia Rodionova in the first round in her first match since winning the French Open earlier this month, but Pironkova made the Russian fight far harder to keep her title bid on course.
The 25-year-old, who won Wimbledon in 2004, had recovered from 5-2 down to take the first set and had just broken to move 3-1 ahead when the tie was suspended due to bad light on Wednesday evening.
Sharapova asked for play to be called off for several minutes before finally getting her wish, but her pleas looked to have backfired when Pironkova hit back to take the second set when play resumed on Thursday.
That provoked an impressive response from Sharapova, who surged through the final set to earn a last 32 clash with Taiwan's Hsieh Su-Wei as last year's runner-up tries to reach the Wimbledon final for the third time.
"I started so slow today, but I guess it's more important how you finish," Sharapova said.
"She loves playing on grass and came out firing. I was a bit tentative and just couldn't get much rhythm.
"But I tried to focus on my game and I'm happy I really stepped it up in that third set."
Pironkova has good pedigree on grass after reaching the Wimbledon semi-finals in 2010 and then making it to the last eight 12 months ago.
And the 24-year-old's talent had shone brightly in the gathering gloom on Wednesday as she raced into a 5-2 lead in the first set.
But Sharapova's return to the top has been fuelled by her ferocious competitive instincts and she willed herself back into the match in typically tenacious fashion.
She saved five set points to force a tie-break, which the Russian took as a series of Pironkova errors gifted the set to the top seed.
With the light fading by the minute, play was called off after Sharapova broke in the fourth game.
But when the match started again on Thursday she struggled to find any rhythm.
Pironkova broke back in the first game of the day and there was no sign of improvement from Sharapova in the tie-breaker, which the Bulgarian took after three double-faults from her opponent.
Faced with the growing possibility of a shock exit, Sharapova suddenly snapped into top gear and blew Pironkova off court, breaking three times to seal the win.