Tennis: 'Scared' Nadal digs deep to overcome Stepanek
Stepanek, an experienced and tricky customer, came out firing and dominated the first set.
Nadal rallied to level but found himself 0-40 down in the sixth game of the decider before eventually pulling out a 2-6 6-3 7-5 victory.
The Spaniard, who next meets another quirky player in Alexandr Dolgopolov, revealed the back injury that severely hampered him in the Australian Open final is still on his mind.
Nadal served eight double faults, and he said: "I was a little bit scared for the back. I am not feeling yet 100pc confident with my serve.
"He is not the right player to play against in the first match because what you want to find is rhythm and against him every point is different."
But the third seed avoided any drama in a 6-3 7-5 win.
It was another bad day, meanwhile, for the US men, with Ryan Harrison, Sam Querrey, Tim Smyczek and Michael Russell all losing.
That left John Isner, who has yet to play his first match, as the only home player left in the men's singles.
Harrison's defeat came against Italian Fabio Fognini, who had an extraordinary rant at umpire Lars Graff over a line call in the second set.
Tenth seed Milos Raonic returned to action after ankle problems with a tight three-set win over Edouard Roger-Vasselin while there were also victories for Tommy Haas, Kei Nishikori and Gael Monfils.
In the women's event, top seed Li Na recovered from 4-2 down in the second set to defeat Chinese compatriot Zheng Jie 6-1 7-5.
Maria Sharapova has turned her focus back to tennis after carrying the Olympic torch into the stadium at the Winter Olympics in Sochi last month. And there was no sign that the Russian has been distracted from her day job as she eased past German Julia Goerges 6-1 6-4. (© Independent News Service)