On Friday, he will meet the iron with the Dutch Robin Haase, who has surprised the Bulgarian Grigor Dimitrov, the 7th-seeded, in three sets of 7-6 (3), 4-6, 6-1.
Victory for Federer on Sunday would earn him a 94th ATP Tour title of his career - levelling Ivan Lendl in second place in the Open Era list - and sixth of a remarkable season.
Nowhere was Federer's wayward performance better illustrated than in the seventh game, when he squandered three break points at 0-40 to allow Ferrer to take a 5-2 lead.
Monfils had won the previous three matches against Bautista Agut, but the Spaniard prevailed this time, saving a match point against him in the third set.
"It pays off playing aggressively here in Montreal, plus I feel comfortable at net, so why not spend some time there instead of slugging it out from the baseline", Federer said. "A bit surprising, to be quite honest, because I hadn't practiced much".
Attacking net with fervor, Roger Federer swept Roberto Bautista Agut, 6-4, 6-4, reaching his first Montreal semifinal in a decade.
Federer, now ranked third, won 6-3 7-6 in Saturday's first semi-final and will next play Denis Shapolov or Alexander Zverev for the trophy on Sunday. It's all about the matches at some stage.
Southampton's scoring woes continue in 0-0 draw vs Swansea
The Swans drew their Premier League opener 0-0 at Southampton on Saturday, with Sigurdsson sitting out as he continues to be linked with a big-money switch to Everton.
Gary Bettman releases statement on passing of Bryan Murray
On January 24, Murray was inducted into the Senators Ring of Honour; he's also a member of the organization's Hall of Fame. Among the National Hockey League executives Murray mentored is Minnesota Wild general manager Chuck Fletcher.
Mourinho ready to continue trend of second-year success
The Brazilian also gave his thoughts on the difference between Conte and Mourinho in their approach to football and coaching. This season, however, each of the Premier League's top seven will play in Europe, which Mourinho believes is a leveller.
A younger Shapovalov had been set to play a five-minute exhibition before Nadal's match, which was ultimately cancelled as another match had gone long. "At the end that's what matters because I spent hours and hours on the practice courts in the past year".
However, there was no such reprieve the next time the 12th seed served, with Federer pouncing on his second break-point opening as his opponent fired a forehand wide.
Both the Rogers Cup and the Western and Southern Open in Cincinnati are tune-up events for the final Grand Slam tournament on the tennis calendar, the US Open, which gets under way on August 28.
The 18-year-old left-hander from Richmond Hill, Ontario beat France's Adrian Mannarino 2-6, 6-3, 6-4 and awaits the victor of the late match between fourth-seeded Alexander Zverev of Germany and Kevin Anderson of South Africa.
After dropping the first three games of the opening set Friday, Wozniacki fought back by beating Pliskova at her own game.
The fourth seeded Zverev broke Shapovalov at 4-4 in the first set then served for the set to silence the partisan crowd. "I wasn't the player I was before my injury", Haase said.
Fourth seeded Alexander Zverev defeated South Africa's Kevin Anderson in straight sets 7-5, 6-4 to set up a clash of rising stars with Shapovalov.