Racing takes center-stage again in downtown Santa Rosa on Sunday morning, but instead of the whooshing of professional riders on their bicycles, spectators will see running shoes on thousands of amateur runners pound the pavement.

The Santa Rosa Marathon, presented by Blood Centers of the Pacific, is in its fifth year and, according to race director Orhan Sarabi, the number of participants has bulged due in large part to the tragedy at the Boston Marathon in April.

In fact, Sarabi said, the Santa Rosa Marathon is the top Boston Marathon qualifier race with regard to the highest percentage of racers registering a time to qualify for the Boston Marathon.

"Everyone wants to get back to Boston," said Sarabi. "Boston helped absolutely to increase the participant numbers and so does the quality of the race and the schwag we give away."

Last year there were 2,004 participants and this year there are expected to be more than 3,500 runners — an increase of more than 50 percent. Additionally, race organizers expect the field for this year's race to be 60 percent women.

In the previous four years of the race, no one has won it twice on either the men's or women's side. Ramiro Guillen, 30, of Goleta, was the 2012 winning male with a time of 2:40:26. Kristi Rossi, 44, of Hillsborough, was the top female finisher (14th overall).

This year's race will feature runners from seven countries (USA, Spain, Australia, Russia, Jamaica, Canada and Mexico) and 48 states.

"We are on the international marathon map," Sarabi said. "There are a lot of people coming in from different states and different locales to race."

The standard entry fee for participants is $90 and registration began last October.

All finishers receive a medal, jacket and a bottle of wine.

The marathon, which was featured in a recent issue of in Runner's World magazine, begins at 6 a.m. and the first finishers are expected between 8:30-8:45 a.m. The race starts and begins at Julliard Park in downtown Santa Rosa (see accompanying box for downtown road closures).

There are two other races, a half-marathon (6:30 a.m. start) and a 5K downtown run (7:15 a.m. start). These races also start and end at Julliard Park.

Sarabi said the event is expecting at least 5,000 spectators spread throughout the course, which was designed by Arthur Webb. The Santa Rosa Marathon, established in 2008, worked with the Santa Rosa Convention and Visitor's Bureau to plan the course and event logistics.

The marathon will start in downtown Santa Rosa for approximately 2 miles and turn onto the Prince Memorial Greenway, go under Dutton Avenue and on to Stony Point Road. Racers will then turn onto Fulton Road and then Willowside Road for a stretch. In a unique part of the race runners will jaunt through Deloach Vineyard & Winery and actually run through the winery's barrel room before heading back to downtown.

More information on race details and logistics, a course map and spectator parking can be found on the Santa Rosa Marathon's official website, thesantarosamarathon.com.