Joey Gamache fights the most pivotal bout of his professional boxing career Sunday night in Portland, where he meets Ramon “Rocky” Martinez for the World Boxing Union junior welterweight championship.

At this stage of his career, every fight could be the last for the 29-year-old Gamache. The former two-time world champion from Lewiston has reached the crossroads after almost nine years as a pro, but he has every intention of taking the high road with a victory over Martinez at the University of Southern Maine’s Sullivan Gym.

Sunday’s fight card begins at 8 p.m., with the feature bout expected to start at 10:30. The Gamache-Martinez fight, in the 140-pound division, is scheduled for 12 rounds. Tickets are $20 and $30 for the event, which is being handled by Michael Acri Boxing Promotions of Erie, Pa.

Gamache, who boasts a 43-2 record with 28 knockouts, is rated No. 5 by the World Boxing Association. He said Sunday’s fight might be his ticket for a return to glory.

“This is the most important fight of my career, most definitely,” Gamache said. “I can’t afford to lose this fight. How many people think I can do it, very few, but I believe in myself, always.”

In the opposite corner is Martinez, a 29-year-old native of Mexico who has spent the last 10 years in Chicago. Martinez, who turned pro in 1992, is 20-1 with 11 KOs. He is rated No. 7 by the International Boxing Federation (IBF).

The only loss suffered by the former Illinois lightweight champ was a 12-round decision against Phillip Holiday last November in the IBF lightweight title fight in South Africa.

The World Boxing Union, the sport’s new challenger among sanctioning bodies, is trying to make inroads against the likes of the long-established WBA and the World Boxing Council (WBC).

“I hope people realize the magnitude of this fight,” Gamache said. “People may question the credibility of the [WBU] title, but Kevin Crowley just won a title on ESPN against Luis Espinoza. And national TV [ESPN2] doesn’t walk in every day.”

Gamache hopes the state’s boxing fans will turn out Sunday to help welcome him back.

“I’m hoping the people come out and support it,” Gamache said. “I’m hoping that the fans stick with me and don’t quit on me.”

Gamache was originally scheduled to battle former three-time world champion Greg Haugen, who sustained a five-inch cut over his eye during a sparring session and had to back out. The result was a date against Martinez and the chance to fight for the WBU belt.

If Gamache wins, he will join an elite group of 19 boxers who have won world titles in three different weight divisions. He earned the WBA junior lightweight (130-pound) crown with a 10th-round knockout of Jerry Ngobeni in 1991, then annexed the WBA lightweight (135) title with an eighth-round KO of Chil-Sung Chun in 1992.

Gamache’s forte as a boxer has always been hand speed. He is able to score by landing numerous punches, but is quick to elude most of his opponents. Gamache does not possess exceptional knockout power, but has enough pop to send foes to the canvas.

Bos describes Martinez as a tactful boxer who is clever in the way he executes his fight strategy.

“He tries to set you up to land his punches,” Bos said. “He’s not a guy you can hit with everything you throw. He comes forward, but he’ll take a step to the side.”

Sunday’s undercard includes a six-round light welterweight fight between Augusta’s Chris Albee (5-0, 4 KOs) and Manny Santiago of Haverhill, Mass. Another six-rounder pits Dale Storey (3-2-1) of Halifax, Nova Scotia, against Zuri Lawrence (2-2-4) of Wappingers Falls, N.Y.

The other bouts are: John Webster (5-2) of Portland vs. Glen Johnson (1-1) of Boston, middleweights, four rounds; and Scotty Wilson (1-0) of Sanford against Muhammad Brooks (7-1) of Nashua, N.H., light middleweights, four rounds.