LONDON - Roger Federer had to claim a pair of tiebreak sets against a player who had never won on a grass court as the seven-time champion was tested on Monday in his opening match at the Wimbledon Championships.

While the third seed had to work to post his 7-6, (7-5), 7-6 (7-3), 6-3 win over Argentine Guido Pella, top seed Novak Djokovic had it all his way 6-0, 7-6 (7-3), 6-4 over Briton James Ward to begin his title defense.

Djokovic raced away by winning the first nine games, and then lost two in a row in the only competitive set of the match.

“I honestly didn’t expect myself to start that well - nine games in a row, 6-0, 3-0,” Djokovic said. “It was just a matter of time when James would win his first game.”

Federer showed resilience as he broke Pella for 5-3 in the third set and served out a tight victory in two hours as light began to fade on Centre Court.

“It felt great, I was happy to walk out on court,” said the winner, whose next opponent will be 772nd-ranked Brit Marcus Willis. “It’s nice to be back here.

“I’ve been working since February to make sure I didn’t miss Wimbledon,” said Federer, who missed the French Open with back pain and underwent a February knee operation.

“I still don’t know if I’m fully fit. This match may have been just what I needed. I was very happy to be there and win it. I’m still on my way back.”

Djokovic, who is looking for his fifth grand slam title, claimed victory in a shade over two hours with an ace on match point.

Ward, ranked 177th, now goes back to the Challenger ranks after his annual showing at the All England Club. The 29-year-old will be hit with a massive rankings drop of around 100 places after making a surprise third-round appearance a year ago.