Nadal, who surrendered the No. 1 ranking to Djokovic last month, went out in the second round in 1-6, 7-6 (5), 7-6 (5) losing to No. 41 Dodig of Croatia.

In the third set, Nadal broke Dodig's serve to take a 5-3 lead and had a chance to serve for the match. But Dodig refused to quit and broke back immediately.

In the tiebreaker, Dodig took a match point with his 19th ace and ended swfitly with a spectacular cross-court backhand, right on the line.

"He played very well- very aggressive," Nadal said. "He didn't feel the pressure in the important moments.”

 Dodig will next face Serbia's Janko Tipsarevic, who beat Spain's Fernando Verdasco 6-4, 6-7 (5), 6-3.

Djokovic, the 2007 Rogers Cup champion, had to survive a scare before defeating 30th-ranked Nikolay Davydenko of Russia 7-5, 6-1 to improve his stunning 2011 record to 49-1 overall and 25-0 on hard courts. The Serbian player's only defeat came at the hands of Federer in the French Open semifinal.

In his first match since turning 30, former No. 1 Federer defeated Canada's Vasek Pospisil 7-5, 6-3 in his first match.

Djokovic said it felt good stepping onto a court as the world's top player, particularly in front of the loud, tennis-savvy Montreal crowd. At the same time, he's trying to stay grounded amid all the extra attention that comes with his new status.

"Being No. 1 is a big responsibility, not just on the court but off the court as well," Djokovic said. "(I'm) just trying to handle it in the best possible way, but on the other side trying to keep my life very simple, the way it was before."

Djokovic was happy to finally get back on court after a four-week layoff, which he partly blamed for falling behind Davydenko 4-1 in the first set. He said switching surfaces from clay to grass to hard court at recent events, and playing an opponent like Davydenko, didn't help either.

"I needed some rhythm, and he didn't give me any," Djokovic said. "I got back into the match. When I needed to use my chance, I did. The second set was much more comfortable for me."

Heavy thunderstorms delayed late-afternoon matches including the one between two-time Rogers Cup champion Nadal and Dodig.

In a late match, American Mardy Fish beat Spain's Feliciano Lopez 6-2, 6-3.

In earlier results, No. 5 Gael Monfils of France defeated American Alex Bogomolov, 6-2, 7-6 (5); No. 7 Tomas Berdych of Czech Republic ousted Alexandr Dolgopolov of Ukraine 4-6, 6-2, 6-3; No. 8 Nicolas Almagro of Spain defeated Ukraine's Sergiy Stakhovsky 6-2, 7-6 (5); No. 10 Richard Basquet of France beat Thomaz Bellucci of Brazil, 6-1, 6-4; No. 13 Jo-Wilfried Tsonga of France blasted 15 aces to beat Bernard Tomic of Australia 6-3, 7-6 (1); No. 14 Stanislas Wawrinka of Switzerland knocked out American qualifier Michael Russell 6-3, 6-2; and Ivo Karlovic of Croatia beat Germany's Philipp Petzschner 6-7 (0), 7-6 (2), 7-6 (6).

For the 21-year-old Pospisil, it was dream to play his childhood idol, Federer, who won the Rogers Cup in 2004 and 2006 and was runner-up in 2007 and 2010.

Federer said it's not the first time he's heard of a younger opponent's admiration.

"For me it was important to have role models to look up to, such as (Pete) Sampras and (Stefan) Edberg and so forth," Federer said. "Then to be able to also play Pete at Wimbledon was very big in my career. It gave me a huge lift to be able to play in a big stadium against a big player and I hope it does the same for him."

When told Federer was impressed by his level of play, Pospisil blushed, let out a nervous giggle and stumbled on his words a little bit.