Tkachuk, No. 2 on NHL Central Scouting's final ranking of North American skaters eligible for the 2016 NHL Draft, has been dealing with the injury since the Ontario Hockey League championship series against Niagara. He played through it in the Memorial Cup, and had five goals and three assists in four games.

BUFFALO -- London left wing Matthew Tkachuk said Thursday he will not take part in any of the fitness testing at the NHL Scouting Combine this week because of a sprained ankle.

"I'm going to hold off on the testing; I'm a little dinged up," Tkachuk said. "There's no point in doing any of the bike tests or the testing right now if I'm not 100 percent. Whichever team drafts me, I'll be excited to test at development camp and see where I rank. We'll see what they think and go from there."

Tkachuk took his medical exam Wednesday and completed the functional movement screen test on Thursday, but will remain off his ankle as much as possible.

On Friday, prospects will take turns on the grueling VO2 Max bike test at HarborCenter. The VO2 Max, one of three tests on Friday, measures the endurance capability of a player's heart, lungs and muscles.

The Wingate Cycle Ergometer peak power output test, a 30-second all-out sprint on a stationary bike that measures a player's explosiveness and could provide critical information in learning how quickly a player might be able to begin a transition up ice, is the last of nine fitness tests to be completed on Saturday at HarborCenter.

Last year, center Jack Eichel, chosen No. 2 by the Buffalo Sabres in the 2015 NHL Draft, exhibited more endurance than Edmonton Oilers center Connor McDavid in the VO2. McDavid, chosen No. 1 in the 2015 draft, lasted 0.7 seconds longer than Eichel in the Wingate.

"I'm watching the facial expressions, the drive they have," Dallas Stars director of amateur scouting Joe McDonnell said. "Obviously, they're going to improve all those skills down the road once they get older and more mature, since the body changes. One thing you can see on the bike is the don't-quit-attitude type thing. Are they going to push it right to the max? You can see that in their face."

The top prospects this year are looking forward to the challenge.

"Oh yeah, there's always stories about the VO2 or the Wingate test," said Cape Breton left wing Pierre-Luc Dubois, No. 1 on NHL Central Scouting's final ranking of North American skaters. "It's going to be fun. I know a lot of the guys there."

Here are four other intriguing takes from Thursday at the combine:

1. First-round feedback: Center German Rubstov (6-foot-2, 178 pounds) grew up playing for Russkie Vityazi Chekhov, the same Russian minor hockey league program as Chicago Blackhawks left wing and 2016 Calder Trophy finalist Artemi Panarin.

The difference is Rubstov is three inches taller and will be selected in the NHL draft. Panarin went undrafted and signed a two-year contract with the Blackhawks on May 1, 2015.

"I like to play fast, but I do consider myself a defensive-center," Rubstov said through an interpreter. Rubstov, No. 5 on NHL Central Scouting's final ranking of international skaters, is no secret at the combine this week; he had 26 interviews scheduled with NHL teams.

Rubstov began playing hockey in Chekhov when he was 4 years old.

"I like Panarin because he's very technical and fast, can beat anybody on the ice and he can score," Rubstov said. "I'll need to work a little more to be as fast as he is right now, though. But I feel I've done enough this season to hopefully be drafted in the top 15."

2. Scout's honor: David Gregory of NHL Central Scouting wouldn't be surprised if Red Deer forward Conner Bleackley gets another chance.

Bleackley was not signed to an entry-level contract by the Arizona Coyotes at the Wednesday deadline and is now eligible to re-enter the 2016 NHL Draft. The Coyotes receive a 2016 supplemental second-round draft pick.

The Colorado Avalanche selected Bleackley with the 23rd pick of the 2014 draft. He was traded to the Coyotes on Feb. 29, along with forward Alex Tanguay and defenseman Kyle Wood, for forward Mikkel Boedker.

Bleackley, 20, had 46 points (13 goals, 33 assists) in 55 games with Red Deer of the Western Hockey League this season but was plagued by knee and wrist injuries.

"Those injuries may be part of the problem and could hold him back," Gregory said. "I think there will be a chance, though. People knew him well enough in his draft year, and he was on a lot of people's lists. They know his developmental curve and there will be some teams that say this makes sense for us.

"If you have a pick later in the draft and there's nothing else that makes sense, I could see Conner getting another chance."

3. Top underrated prospect: Right wing Cliff Pu, No. 75 on NHL Central Scouting's final ranking of North American skaters, could turn out to be a player capable of generating secondary scoring in the NHL one day.

He did it for London in the OHL all season. Pu (6-1, 192) had 31 points (12 goals, 19 assists) in 63 regular-season games, eight goals and five assists in 18 OHL playoff games and one goal and two assists to help London to the Memorial Cup championship in four games.

"He started the season out with an injury, but upon his return was able to inject speed and skill into the London lineup," Matt Ryan of NHL Central Scouting said. "He has good size and is an excellent skater. He is quick, agile and deceptive with the puck, and his speed puts opposing defensemen under a ton of stress, and that makes him difficult to play against, especially on the penalty kill."

Pu developed good chemistry with left wing Max Jones, No. 14 on Central Scouting's final ranking of North American skaters. They provided London with secondary scoring after the top line of Tkachuk, Mitch Marner and Christian Dvorak.

"I'm a pretty good skater, and like to use my speed to my advantage," Pu said. "I like to set up my teammates, so I'm a good two-way center who can make the good pass."

4. Quirky question of the day: Val-d'Or right wing Julien Gauthier, No. 12 on NHL Central Scouting's final ranking of international skaters, was asked to rank in order of importance five categories.

"They asked me to put in order of importance hockey, friends, team, girlfriend and family," Gauthier said. "But you really don't know what they're looking for. I put in as family, hockey, team, friends and girlfriend. Maybe that's what they were looking for."