It's been a tough few days for Andre De Grasse.

The 29-year-old from Markham, Ont., finished third in his Olympic men's 200-metre semifinal heat at 20.41 seconds Wednesday at Stade de France. He was officially eliminated from Thursday's final when the third and fourth finishers in the next semifinal posted better times.

Afterward, De Grasse revealed he had a hamstring injury that first surfaced a month ago. He only missed a week of training before re-aggravating it this week.

"It was gonna be tough today," De Grasse said. "I warmed up and I kind of didn't really feel it but I knew I just wanted to try and try and do my best and see what I could come up with."

WATCH | Defending champion De Grasse out of Olympic men's 200m final: 

Reigning Olympic champ Andre De Grasse eliminated in men's 200m semifinal heats

Tokyo 2020 200-metre champion Andre De Grasse of Markham, Ont., finished third in his 200m heat, which was not enough to qualify for the final at Paris 2024.

"I didn't realize [the injury] until after the 200m first round [on Monday]," he added. "I was warming up during the 200m heats, I thought it was just a little bit of soreness and then later that day, I got an ultrasound and just really enflamed the hamstring.

"They said I could go, gave me some meds for the pain and I just tried to come out here today and do what I could do but I knew it was gonna be tough to try to come away with a fast time."

De Grasse won gold in the event at the Tokyo Games with a personal best of 19.62 seconds.

The six-time Olympic medallist also missed the 100-metre final on Sunday, the first time in his career that he missed an Olympic final in the 100, 200 or 4x100 relay final.

WATCH | De Grasse says he re-aggravated hamstring injury: 

Andre De Grasse says he may have re-aggravated a hamstring injury before elimination in 200m semis

After being eliminated in the Olympic men's 200-metre semifinals, Andre De Grasse tells CBC Sports' Devin Heroux that he may have re-aggravated a hamstring injury.

De Grasse racing without personal coach

De Grasse admitted that the situation with his coach, Rana Reider, having his accreditation revoked on Tuesday, also served as a distraction.

Without getting into specifics, the Canadian Olympic Committee said it found new information on Sunday "about the appropriateness of Mr. Reider remaining accredited by Team Canada at the Paris 2024 Games. In discussion with Athletics Canada, it was agreed that Mr. Reider's accreditation be revoked."

U.K. media outlets have reported the decision is tied to concerns over the "safeguarding" of athletes and allegations of sexual and emotional abuse, and court documents filed in Broward County, Fla., show three women have filed suit against Reider related to alleged sexual and emotional abuse.

Stevens said Reider currently has no sanctions against him by the U.S. Center for SafeSport, USA Track & Field or Athletics Canada.

"I tried to keep my head up and stay mentally strong but of course, that's always a tough one," De Grasse said. "Not having your coach out there who leads you through these Games and being with you all year, so definitely is a tough one."

'I didn't know the issue'

De Grasse said he found out at the same time as everyone else.

"I didn't know the issue," he said. "Of course, I left [him] back in 2023 when everything went down, he served his time, everything was good, I went back. My federation, everybody said it was good to go, he was all cleared.

"They gave him accreditation and all of a sudden I guess there was a new case. I knew nothing about it, kind of just sprung on to me the same time you guys knew. So of course that's a tough one to swallow to try to just know about that right before you're about to run."

With the 4x100 relay opening round coming on Thursday morning, De Grasse said he'd "try to support my team any way I can."

Lyles to race for 2nd gold

Noah Lyles will race for his second Olympic gold medal despite finishing second in the 200-metre semifinal, his first loss at that distance in three years.

It opened up a 24-hour period to debate and discuss the meaning of the second-place finish, which still earned Lyles an automatic qualifying spot in Thursday night's final but could have him running the curve from a less-than-ideal lane.

Last weekend, Lyles notably lost both his opening heat and the semifinal round of the 100, before coming back to eke out a .005-second victor y over Jamaica's Kishane Thompson in the final. That win came about 90 minutes after another Jamaican, Oblique Seville, beat him in the semifinal for that sprint.

Quincy Hall grabs out-of-nowhere men's 400m win 

Quincy Hall became the latest American to electrify Olympic track and field with an out-of-nowhere comeback Wednesday night, sprinting from far behind in the 400 meters to reel in three runners and capture the gold medal.

Hall, buried in fourth place as the runners rounded the last bend, outran the runner on his outside, then two more to the inside to cross the line in 43.40 seconds, the fourth-fastest time ever, then dropped to the track to do snow angels to celebrate.

Britain's Matthew Hudson-Smith finished second and Muzala Samukonga of Zambia finished third.

Hall is the first American since LaShawn Merritt in 2008 to capture gold in the one-lap race. His victory came an evening after American Cole Hocker came from far behind late to beat the favourites in the men's 1500.

WATCH l Quincy Hall overtakes Great Britain's Matthew Hudson-Smith for men's 400m gold:

American Quincy Hall rallies to win gold in electric Olympic 400m final

Quincy Hall overtook Great Britain's Matthew Hudson-Smith in the final few metres to win Olympic gold in the men's 400m race.

Other Canadian results

Earlier Wednesday, Moh Ahmed failed to advance to the 5,000-metre final after falling in his heat.

The 33-year-old from St. Catharines, Ont., was in the top seven with about 400 metres left in the race when he seemingly tripped over the leg of a runner in front of him and took a fall. A handful of other runners fell not long after in a similar fashion.

Quebec City's Jean-Simon Desgagnes finished 13th in the men's 3,000-metre steeplechase final in a time 8:19.31. Soufiane El Bakkali or Morocco claimed the gold in 8:06.05.

In the men's 800, Edmonton's Marco Arop qualified for Friday's semifinals finishing second in Heat 1 with a time of 1:45.74. Arop is the reigning world champion in the event.

Mariam Abdul-Rashid of Oshawa, Ont., made it into the women's 100 hurdles semifinals grabbing one of three non-automatic qualifying spots with a time of 12.80 seconds and placing fifth in Heat 3.

WATCH l El Bakkali defends Olympic steeplechase title:

El Bakkalli defends Olympic title as steeplechase world record holder Girma injured after crashing into barrier

Morocco's Soufiane El Bakkali defended his Olympic title in steeplechase, after world record holder Lamecha Girma of Ethiopia crashed into a barrier on the final lap, and had to be carried out on a stretcher.