Under a new sponsorship agreement, Under Armour will provide finishers in Sunday’s Honolulu Marathon with one of the event’s prized keepsakes.

The sports apparel and footwear company is the new "official running partner" of the Honolulu Marathon and will produce the shirts awarded to those who complete the 26.2-mile course on Sunday, among other considerations in the deal.

Honolulu Marathon president Jim Barahal said details of what is expected to be a multi-year contract are being finalized, and the company will provide approximately 40,000 shirts and 10,000 hats as part of the pact.

Barahal said the marathon’s partnership with Under Armour and Dome Corporation, which markets the company’s products in Japan, was confirmed in August.

"It’s extraordinary on their part in a very short timetable to put this together," Barahal said.

Workers at the Hawaii Convention Center were busy Monday morning assembling an expansive Under Armour display area that will herald the company’s association with the race at the Honolulu Marathon Expo, which opens Wednesday.

With Under Armour making inroads into the running market, Barahal noted the marathon’s connection to Japan as an attraction for the Baltimore, Md., based company, which also sponsors University of Hawaii athletics.

Barahal said the marathon receives an undisclosed amount in cash in addition to a "significant amount of value in kind," including the finisher and staff shirts and hats. Under Armour will also produce official marathon merchandise available for purchase at the expo.

"I thought this might be a natural event for them even though they weren’t traditionally involved in major marathons … and knowing the quality of the brand," Barahal said.

"Certainly one of the big appeals of the Honolulu Marathon for them is the large Japanese participation in the race."

The Honolulu Marathon is on track to finish the year as the fourth largest race in the country, trailing the Boston, New York and Chicago marathons. The race drew 31,579 entrants last year with 22,096 finishing the race.

Barahal said Monday that approximately 29,600 entries had been received with another 1,000 expected to take advantage of late registration at the expo. Another 3,500 are entered in the annual 10K race-day walk held in conjunction with the marathon.

Race packets must be picked up at the convention center before the marathon expo closes at 5 p.m. Saturday.

Last year’s men’s and women’s champions will be among the professional runners at the head of the throng when the 42nd Honolulu Marathon begins under a fireworks show at 5 a.m. Sunday along Ala Moana Boulevard.

The course turns into downtown Honolulu, continues through Waikiki, around Diamond Head and into East Oahu. The runners will loop through Hawaii Kai before heading back down Kalanianaole Highway, making a second climb around Diamond Head on their way to the finish at Kapiolani Park.

Gilbert Chepkwony of Kenya and Ehitu Kiros of Ethiopia return to defend their titles. Chepkwony pulled away from two-time champion Nicholas Chelimo during the stretch through Kahala to win last year’s race with a time of 2 hours, 18 minutes, 47 seconds.

The top three women’s finishers in last year’s race are set to return on Sunday. Kiros made a late move down Diamond Head to win the women’s race at 2:36:02, eight seconds ahead of 2011 champion Woynishet Girma. Valentina Galimova, the 2012 women’s winner, came in three seconds after Girma.

Lane closures along the route will begin at 12:30 a.m. Sunday. Information on specific closures are available at honolulumarathon.org/event-info/traffic-advisory/.