IBF welterweight champion

Forrest met Frank again in a rematch at Madison Square Garden on May 12, 2001, on a Félix Trinidad undercard. Forrest dominated his opponent and won the fight by a unanimous decision to claim his first major professional boxing title.

Forrest vs Mosley I

In 2001, Forrest fought the WBC and lineal welterweight champion, Shane Mosley.^[3] Many considered Mosley to be the best fighter in the world, and he was the betting favorite to win the fight. Despite being the favorite, Mosley was dominated in this bout. Both fighters initially started strong, landing hard blows, but in the second round Forrest had Mosley hurt early and knocked him down for the first time in his career. A series of strong punches would put him down yet again later in the round. With his dominant performance, Forrest was also awarded the Ring Magazine welterweight title.

Forrest vs Mosley II

Six months later, Forrest once again squared off against Mosley in a rematch. Despite a stronger performance from Mosley, Forrest won a clear cut decision, using his jab more effectively and through superior ring generalship. Forrest was now considered by many to be one of the top fighters in the world.

Forrest vs. Mayorga I

In January 2003, Forrest fought the WBA welterweight champion, Ricardo Mayorga. Mayorga was a mostly unknown fringe contender from Nicaragua and few gave him a chance to win against the significantly bigger and stronger Forrest. Mayorga shocked the world when he easily dominated Forrest, dropping him once in the first round and again in the third round. The referee would call off the fight after the second knockdown, as Forrest was visibly dazed and unable to get his footing.

Forrest vs. Mayorga II

Forrest would rematch Mayorga six months later, losing again, this time by a majority decision. The bout was close and competitive, with Mayorga mostly chasing Forrest around the ring while Forrest was content to fight from the outside.

Comeback trail

Forrest took two years off from fighting because of injuries; Forrest had complete reconstructive surgery on his left arm. He had three surgeries two on his shoulder to repair a torn rotator cuff and one on his left elbow to repair torn cartilage and nerve damages.

In his first fight since losing twice to Mayorga, Forrest knocked out Sergio Rios in two rounds. After the fight against Rios, Forrest stopped Elco Garcia in the tenth round.

Forrest won a controversial ten round unanimous decision over Ike Quartey on August 5, 2006, at Madison Square Theatre, New York City. The judges at ringside scored the fight, 95–94, 95–94, and 96–93.^[4]

WBC Light middleweight champion

On July 28, 2007, Forrest won a unanimous decision against Carlos Baldomir in Tacoma, Washington, frequently firing off heavy right blows at Baldomir. After twelve rounds, Forrest won a lopsided 118–109, 116–111, 118–109 decision to take the vacant WBC light middleweight title.

On December 1, 2007, at Foxwoods Resort Casino, he successfully defended his light middleweight title against Italian Michele Piccirillo, scoring an eleventh-round TKO.

Forrest vs. Mora

On June 7, 2008, Forrest lost his title to The Contender winner Sergio Mora via a 12-round majority decision. In the build-up to the fight, Forrest referred to Mora as "the pretender" and threatened to send him "out on a stretcher".^[5] However, Mora succeeded in pulling off the upset victory.^[6] The final scores were 114–114, 115–113 and 116–112 in favor of Mora.^[7][8]

Reclaiming the title

Forrest reclaimed his WBC 154-pound title on September 14, 2008, against Sergio Mora via unanimous decision, the judges scores were 118–109, 117–110, and 119–110.^[9]