Rory MacDonald is one tough competitor

Before the decisive fifth and final round of his January Bellator MMA welterweight title fight at the Forum, Rory MacDonald surveyed the painful swelling that had emerged in his left leg, and later joked it appeared a new life form was taking shape.

“I knew I had to impose my will, attack and get in a dominant position,” MacDonald said. “You have to tell yourself in any hard situation to keep pushing through it.”

By getting then-champion Douglas Lima to the canvas and holding him there to win the belt, MacDonald underscored the lessons he’d gained in some of the most gritty mixed martial arts fights ever and defined himself as one of the sport’s most determined competitors.

Now, with some expressing concern Canada’s MacDonald is taking on too much risk by doubling down on the welterweight belt by seeking to defeat middleweight champion Gegard Mousasi (44-6-2) in Saturday’s main event, he’s prepared to showcase his knack to display “that will to overcome.”

“It will be a hard-nosed fight and I’m ready,” MacDonald (20-4) said. “Sometimes, it gets uncomfortable in there to push through those barriers. I’ve had to push myself and break down walls.

With victories over current UFC welterweight champion Tyron Woodley and popular former lightweight title challenger Nate Diaz on his resume, MacDonald came to Bellator with a 2010 fight-of-the-night loss to Carlos Condit and the bloody 2015 “fight-of-forever,” as UFC President Dana White called it — a welterweight-title loss to Robbie Lawler — keenly in mind.

“When you lose a fight knowing you had more in the tank or that you should’ve done something different, those regrets haunt you,” MacDonald said. “You learn from that, so it never happens again. It makes you better.”

MacDonald, 29, was a fast learner developing the multiple MMA disciplines after shifting from hockey at age 14.

“I was passionate, enjoyed it, and was consumed in it 24/7 at a young age. I fell in love with it. I liked all the disciplines, so that’s why I excelled,” he said.

Beyond striking, wrestling and martial arts, MacDonald has ascended to elite stature because of his uncommon resilience. In the Lawler fight, for instance, his nose was badly broken, yet he remained upright, slugging away in moments that have stopped others.

“I learned from the disappointment and convinced myself the next hard situation would be something I can overcome. Lawler didn’t finish how I liked, but the Lima fight did. I pushed through,” he said.

Among the many admirers is Lima, who opens Bellator’s eight-man welterweight tournament Saturday with a third fight against former champion Andrey Koreshkov.

“A guy who can withstand that damage deserves so much respect,” Lima said. “The last round decided the fight. I should’ve moved around. He was so badly injured. I should’ve finished him off. But he’s been through some wars and he’s considered one of the best, and here I am crying about it now.”

MacDonald said “to get that respect is a nice bonus … I’ve put a lot on the line.”

Against fellow UFC defector Mousasi, MacDonald anticipates “a lot of strategy. Both of us are tricky, both have a lot of experience and high skill level. It’s a chess match as much as it’s going to be a physical battle. I’ll see when I’m in there how to figure it all out. He’s very powerful, has a lot of strength and if he gets in a dominant position he can impose it.

“But I like to test myself. When I was a kid, I wanted to be a multi-weight champion. I have the skills, the experience, my youth and physical abilities. So if there’s ever a time to go for these challenges, my chance is today.”

lance.pugmire@latimes.com

Twitter: @latimespugmire