ROME (AFP) - Roger Federer joined Novak Djokovic and Andy Murray in reaching the third round of the Rome Masters on Wednesday with the Swiss admitting that he was fully expecting to lose against Alexander Zverev.

"I'm cautious but extremely happy - I was expecting to lose in straight sets today," admitted the 17-time Grand Slam champion, who withdrew last week from Madrid with back pain.

"That was the mindset going in. To win in straights is actually a really big surprise to me.

"I only decided after the warm-up that I was actually going to play. For me it was a big match on many levels."

The 89-minute match was the first for the 34-year-old Swiss since losing a Monte Carlo quarter-final to Jo-Wilfried Tsonga nearly a month ago.

Even in victory, Federer said that he would decide at the last minute whether he can take to the court on Wednesday against 13th seed Dominic Thiem, a 6-3, 6-2 winner over Joao Sousa.

"I don't know how I'm going to feel tomorrow. I hope (I can play). I'm literally going practice after practices. It's baby steps right now.

"So to even think of tomorrow is already a big ask."

Top seed Djokovic and number two Murray produced no-drama victories, with the Serb beating Stephane Robert 7-5, 7-5 while Murray put out Kazakh Mikhail Kukushkin 6-3, 6-3.

Federer is playing here for the 16th time as he seeks his first Rome title. The Swiss has finished runner-up four times, most recently last year against Djokovic.

Rome marks only the fourth tournament of the season for Federer, who underwent knee surgery in early February, the first operation of his career.

Victory over Zverev sent Federer's record in 2016 to 11-3.

Zverev, aged 19 and ranked 44th, could not have asked for a more challenging Rome debut as he faced off against his tennis idol. His loss left him 0-8 against top 10 opponents.

Federer broke for 4-2 on his way to collecting the opening set in 28 minutes.

The Swiss then earned a break in the third game of the second set but then lost serve for 2-all.

The veteran broke back on his fourth opportunity in the 11th game for a 6-5 lead and finished off the welcome win a game later, a drop shot setting up two match points with Zverev driving wide on the first.

In women's second-round play, Eugenie Bouchard handed second-seeded Australian Open champion Angelique Kerber a 6-1, 5-7, 7-5 defeat, her second straight in an opening match after losing last week in Madrid.

"In the first one-and-a-half sets I was completely not playing my game and I was completely not on the court," the German said.

"I was just trying to fight back. I was not playing my best tennis. But of course I was fighting and the third set was really close. At the end she played good and won the last point." Spanish third seed Garbine Muguruza crushed Russian Ekaterina Makarova 6-1, 6-0 while Madrid quarter-finalist Irina-Camelia Begu of Romania upset injured fourth seed Victoria Azarenka 6-3, 6-2.

The Belarusian withdrew with lower back pain last week from Madrid and was unable to fight off her Rome challenger after winning all five of their previous meetings.

"I was trying but it didn't work," Azarenka said.

"The back is not good right now. I'm very disappointed obviously with that.

"I thought I was okay and was ready to play and came back, so I'm just disappointed. We'll see what happens. I'm not going to think about the future."

Swiss 11th seed Timea Bacsinszky defeated Lesia Tsurenko 6-2, 6-4 and American Christina McHale beat 13th seed Ana Ivanovic 6-7 (3/7), 6-4, 6-1.