Standing between Federer and another trophy is Frenchman Jo-Wilfried Tsonga, who claimed his third straight upset by dispatching seventh-seeded Bulgarian Grigor Dimitrov 6-4 6-3.
After knocking off world number one Novak Djokovic in the third round, twice champion Andy Murray in the quarters and Dimitrov in the semi-finals, the powerful Frenchman will need to produce one more upset to deny Federer a third Canadian title.
It will be Federer's 120th career final while Tsonga will be playing for a title for the 20th time.
Federer said Tsonga would be on a high after his series of upsets in Toronto.
"I think it was a matter of time that he got it all together again, especially in terms of confidence," said the second seeded Swiss, who is looking for his third title of the season.
"So for him to beat Murray and Djokovic... it's a really good effort for him and it's going to give him loads of confidence going into the finals.
"He just can overpower guys, serve up a storm and then play really aggressive with his forehand and also be solid in his backhand.
"You think you're in a safe place sometimes in the rally, and he takes one step and, you know, just hits it and the point is over."
Federer, who celebrated his 33rd birthday on Friday, was in imperious form, dropping just four points on his serve in taking the opening set.
The 17-time grand slam winner kept up the pressure in the second with a break to open the set and was never seriously challenged, running his record against Lopez to 11-0.
"I think I played extremely well in the first set and was able to make Feliciano probably over-serve and over-hit a little bit and make him feel the pressure from the baseline," said Federer.
"Second set probably wasn't as good in quality but I got the break early."
Dimitrov, rated one of the top young talents on the ATP Tour, had lost all three head-to-head meetings with Tsonga but with three titles under his belt this season stepped onto a sunny centre court as the favorite.
The scrappy Bulgarian traded shots with the muscular Frenchman in a tight opening set but could not convert any of his four break opportunities.
Tsonga, who also has a reputation as a battler and bears a resemblance to a young Muhammad Ali, showed his stomach for the fight from the opening serve and his determination was rewarded with the only break of the first set, going up 5-4 then holding serve for a 1-0 lead.
The second set was not as close, Tsonga breaking in the third game to take control and then again to clinch the match, raising his fist into the air and shadow boxing his way out to centre court where he acknowledged the crowd.
"I'm waiting for this moment since a couple of years now," said Tsonga, who has enjoyed success on the Canadian hardcourts, reaching the semi-finals in three of four visits but advanced to the finals only once.
"It's good because I always believe in myself during all these years and all this week where I lost against those guys and finally I get a little reward."
- Sports & Recreation
- Jo-Wilfried Tsonga
- Grigor Dimitrov
- Novak Djokovic
- Andy Murray