Kulemin is out with a bone chip in his ankle suffered when he blocked a shot in practice Friday.
"It's just a small bone broken in the ankle," coach Randy Carlyle said. "To say it's not a significant injury would be incorrect. It's one of those things."
The 27-year-old right-winger could have played on the injured ankle for a month because it wasn't a displaced fracture, Carlyle said, but the team and doctors decided not to talk that chance. Kulemin is wearing a walking boot to immobilize the ankle.
The Leafs called up Spencer Abbott from the AHL's Toronto Marlies to take Kulemin's spot alongside Joffrey Lupul and Nazem Kadri beginning with Saturday night's home opener against the Ottawa Senators.
"He had a strong training camp for us and when he went back to the Marlies in the two exhibition games, from their coaching staff's advice, he was clearly the best player on the ice," Carlyle said. "So in our minds, that's what we asked for: Who was the best player in the situation when we lost Kulemin and we need a player that's going to come in and play higher in our lineup than what we have here, so we've done that."
A couple of weeks ago it looked like the Leafs wouldn't have any shortage of options. Clarkson was slated to play big minutes on the right side, but the free-agent acquisition won't be available to play until Oct. 25 at the Columbus Blue Jackets after being suspended for the first 10 regular-season games for leaving the bench to enter an altercation in the pre-season.
Toronto traded Joe Colborne, who would have likely been the top option to replace Kulemin, to the Calgary Flames for a fourth-round pick. The cap-strapped Leafs would have had to put the 23-year-old through waivers and risk losing him for nothing if they kept him around but he did not remain on the NHL roster.
But those moves put the team in even more of a bind with Kulemin shelved. His spot on the penalty kill will have to be filled by committee, with Carlyle mentioning James van Riemsdyk, Dave Bolland, Mason Raymond, Carter Ashton, Troy Bodie and even Tyler Bozak as options.
"We're going to need other people to step up and fill those minutes because as far as our first penalty-killing (forward) pair it was Kulemin and (Jay) McClement, so now we have to have somebody else step into that role," the Leafs' coach said.
Kulemin had two assists in the Leafs' first two games of the season.