Lupul returned to the lineup Saturday after missing one game due to injury, but left after two periods. He has 22 goals and 44 points in 69 games this season.
"He is going to have surgery done on his knee," coach Randy Carlyle said. "It's a meniscus procedure and will be done arthroscopically. It will be three weeks to a month recovery."
The Maple Leafs, who begin a three-game road trip to end the regular season Tuesday at the Tampa Bay Lightning, are three points behind the Columbus Blue Jackets for the Eastern Conference's second wild-card spot in the Stanley Cup Playoffs. The Blue Jackets also hold a game in hand.
That was something I've been dreaming of, something I've told myself before the third period I was going to do ... It was an amazing feeling. It's hard to describe. I didn't believe it went in at first but when I saw all the reaction and all the fans going crazy and my teammates going crazy, it's just an unbelievable feeling. I didn't know what to do. I didn't know whether to jump or just skate and do a Theo Fleury. I don't think I'm the same caliber player he is so I couldn't do it.
— Flames forward Mikael Backlund on scoring the overtime winner against the Ducks in Gm. 3