World number three Roger Federer had to use all his guile and experience to battle back from a set down to see off fast-rising Canadian Milos Raonic 4-6 7-5 7-6 in the Madrid Open second round on Wednesday.

The Swiss maestro, after an opening-round bye at the Masters Series claycourt event, was playing his first match since the end of March and only just edged out the big-serving 21-year-old who thumped 21 aces on the Manolo Santana showcourt.

Rafa Nadal made much smoother progress into the last 16, dispatching former world number three Nikolay Davydenko 6-2 6-2 before joining widespread criticism of the unfamiliar blue courts, a controversial innovation at this year's tournament.

Nadal not happy with blue

World number one Novak Djokovic slammed the organisers after his laboured win on Tuesday, saying the surface at the futuristic Magic Box arena was too slippery and complaining the concerns of the players were being ignored.

Officials say the blue courts make it easier for TV viewers to follow the yellow balls but Nadal called for the traditional red clay to be reinstated next year.

"The court is not one that makes you feel comfortable," said Nadal who won back-to-back clay titles in Monte Carlo and Barcelona before heading to Madrid.

"The court is difficult, it's very slippery and it makes supporting movements and getting back to defend very tough," the world number two told Spanish TV.

Nadal next faces 15th-seeded compatriot Fernando Verdasco for a place in Friday's quarterfinals.

"The only thing we can do now is turn the page and we are not going to get the red courts back tomorrow so we have to adapt to the blue," he added.

Federer struggled to make any impression on the Raonic serve in the early stages and was broken himself in the ninth game before the Canadian served out to take the first set.

Drop shot

The 16-times grand slam singles champion levelled the match with an exquisite drop shot before surviving several scares on his serve in the deciding set and then running away with the tiebreak 7-4 as the young pretender's nerve failed him.

Federer, chasing a fourth title of the year, sealed victory on his first match point with a ripping forehand return that caught the line and set up a meeting with French 14th seed Richard Gasquet.

The 30-year-old Swiss said it was slippery at the back of the court against world number 23 Raonic.

"It was pretty much a big struggle for me tonight but sometimes these kinds of wins can create good things," added Federer.

Raonic said he needed to improve his game against the better players.

"I felt I played really well the whole time and I was dictating the match especially on my serve," the Canadian explained.

"It just came down to one or two points but if I want to be in this position against Federer, Nadal, Djokovic ... I'm going to have to improve my returns.

"It's hard not to be disappointed but at the end of the day it's motivating and I know I can get better. With experience, time and a few lucky breaks it will go my way," said Raonic.

Isner lose to Cilic

Elsewhere, American eighth seed John Isner lost 7-6 7-6 to fellow giant Marin Cilic of Croatia.

The unseeded Cilic, who is 1.98 metres (6-foot-4) tall compared to Isner's 2.06, produced the shots when it counted in the tiebreaks, winning the first 7-4 and the second 7-3 to set up a meeting with former U.S. Open champion Juan Martin Del Potro.

Isner refused to blame his defeat on the court, saying he was beaten by the superior player.

"I lost because I didn't do what I should have done out there and he was better than me," he added.

"I always felt this tournament even with the red clay was the most slippery I've ever played on," added the 27-year-old. "It's tough for a big guy like me but my opponent was also a big guy."