Frank Mir against Brock Lesnar during their heavyweight title bout during UFC 100 on July 11, 2009 in Las Vegas, Nevada. (Jon Kopaloff/Getty Images

Report: Brock Lesnar's return is imminent, with plans pursued for the WWE Universal championship

Lesnar announced his retirement after testing positive, which also meant he was out of the USADA testing pool.

Brock Lesnar's high-profile rivalry with Jon Jones will apparently lead to a UFC heavyweight bout, and that means a title change at SummerSlam could be coming, according to Sports Illustrated's Justin Barrasso.

According to the report, Lesnar's return to UFC is "imminent," but he won't leave WWE before his contract is up, fulfilling obligations at the Royal Rumble and WrestleMania 34. The stipulation of Lesnar leaving WWE if he loses the belt would then come into play, as Barrasso notes, in order for Lesnar to get in shape (most likely) for the Jones fight:

As for the WWE Universal title, Barrasso notes Paul Heyman has been pushing behind the scenes to give Samoa Joe a run with the title. There's also a possibility that Baron Corbin cashes in the Money in the Bank contract, ruining the chance that Joe, Braun Strowman or Roman Reigns walk out as champion.

Jones returned to the Octagon after a year layoff to knock out Daniel Cormier and reclaim the light heavyweight championship on Saturday night. After the bout, Jones took the opportunity to tell Lesnar to come back and feel what it feels like to get his "ass" kicked by a fighter 40 pounds lighter.

Jones has won his last 14 consecutive fights.

While the UFC card in Madison Square Garden would be a grand spot for them to show down, Lesnar won't be eligible to return until December due to his USADA suspension stemming from his victory over Mark Hunt:

Earlier last week, rumors spread that Lesnar (5-3 MMA, 4-3 UFC) could face light heavyweight champion Jones upon his return. However, there are several factors that need to be addressed, according to The Wrestling Observer Newsletter's Dave Meltzer (subscription required).

"The working plan is for Brock Lesnar to face Jon Jones, provided Jones beats Daniel Cormier this week, with the idea of late December. But that time frame may not work since Vince McMahon would have to approve of any date until April. We were told that Lesnar vs. Jones was the working idea from a number of sources, but one said that it wouldn't happen that early and would have to be in 2018."

Jones previously discussed the possibility of facing Lesnar during a UFC Facebook chat this week. The former champion said he'd be interested in the fight, but wasn't confident it would happen.

"He's a massive dude," Jones said. "It would be a massive draw, really big for the sport. It would be a great challenge; that's a big old boy.

"I doubt Brock Lesnar would take that fight, though. I definitely wouldn't try to wrestle with him the whole time. I'm not going to tell you what I would do."

Lesnar responded during an interview with APNews.com on Wednesday, claiming he'd accept the challenge.

"Would I fight Jon Jones? Anytime, anywhere," Lesnar said. "Right now, he should be worried about 'DC' on Saturday night."

Meltzer reported that Lesnar had gotten back in the USADA testing pool for UFC.

However, Lesnar's UFC future is still a matter of speculation as he remains under contract with WWE until April 2018 and is currently serving a one-year suspension for two failed drug tests for Hydroxy-Clomihpene.

Lesnar was suspended after a July 9 test turned out to be positive and his one-year suspension was frozen in mid-February, which means it still has five months remaining and the former champion won't be able to compete again until mid-December.

Lesnar announced his retirement after testing positive, which also meant he was out of the USADA testing pool.

According to Meltzer, the rumors of Lesnar and Heyman visiting UFC's offices were denied by sources, however, those within UFC did confirm interest in Lesnar making a return to the octagon.