PORTLAND — It’s going to be wet, but the show will still go on at the Charlie’s Portland Maine Open this week at Riverside Municipal Golf Course.

“We’re going to play and do the best we can,” Maine State Golf Association Executive Director Nancy Storey said Monday after the event’s pro-am. “That’s all we can do. As much as we’d like to, we can’t control what the weather is doing. We do have a rain date of Thursday just in case, but we owe it to the golfers and to the course to try to get it in Tuesday and Wednesday.”

Golfers around the state have been victimized by a seemingly steady dose of rain. After enduring dryer-than-normal conditions through most of the middle part of spring, rain helped green out most of the state’s courses in a hurry. Now many of them, including Maine Open host Riverside, are trying to stay above water.

“It’s made things challenging,” Storey said, “but the staff here at Riverside is doing a great job. The fact that we played (the pro-am event Monday) is nothing short of a miracle.”

The Maine Open, in its 91st year, merged this year with the Portland Open, which would have been in its 14th season. Riverside has hosted the Maine Open 41 previous times. For the past three years, the event was at Fox Ridge Golf Club in Auburn.

When the tournaments were combined, it moved back to Riverside, where the Maine Open was also held from 2002 to 2005.

“We just found, in talking with all the players, they prefered to be closer to Portland,” Storey said earlier this season. “That’s not taking anything away from the work Fox Ridge has done. They were a tremendous host. But with the economy the way it is, we saw an opportunity to merge the two tournaments into one and focus our efforts there.”

The players have responded.

A total of 162 players — a capacity field — will tee it up at Riverside on Tuesday to compete in the newly-named tourney.

And bucking a national trend, thanks to the merger, the Maine Open will actually offer a larger prize purse this year. The overall champion will earn $10,000, and more than $60,000 in prizes will be awarded.

“I’m sure that’s part of the reason we saw more entries, too,” Storey said. “That, combined with some of the mini-tours folding this year.”

In all, there will be five divisions, including Open Pro, Amateur, Maine Pro, Senior Pro and Senior Amateur.

The other major change this season is the length of the tournament. Now just a two-day, stroke-play event, the Maine Open will run, weather permitting, of course, Tuesday and Wednesday.

While defending Maine Open champion John Hickson and defending Portland Open champ Jeff Curl will not be in the field, there are plenty of bigger names taking their places, including 2003 and 2005 champion Kirk Hanefeld, who enjoyed his best season as a touring professional in 2008, earning $183,000 on the Champions Tour. Highlights included a stint atop the leaderboard at the Senior British Open, one top 10 and four top 25 finishes. This year, Hanefeld has made three cuts in three events and ranks 100th on the Champions Tour money list.

In all, there are 12 former winners in the field, 10 from the Maine Open and two from the Portland Open. Jim Renner, the 2007 Portland Open Champion, will join last year’s Davis Richardson Senior Division winner Bob Darling of Fox Ridge and 18-year-old Maine Amateur Champion Ryan Gay in the first group off the first tee Tuesday.

Because the field is so large, the starting times will be broken into four waves, and both the first and the 10th tee will be used for the starting times. Tee times run in the morning run from 7:30 to 9:27. Times then begin again at 12:20 and will run to 2:17. A total of 39 amateurs, 31 Maine pros, 21 senior pros and five senior amateurs are expected to tee it up Tuesday. The entire field will be re-paired for Wednesday’s final round based on first-round scores, with the leaders slated to tee off at about 2 p.m.

Former Maine Open winners in the field include Don Robertson (1981), Joe Clark Jr. (1992), David Cummings (1994), Jerry DiPhillippo (1995), Kyle Gallo (1999), James Gilleon (2001), Ryan Ouellette (2002), Hanefeld (2003 and 2005), Shawn Warren (2004) and Ricky Jones (2006).

The other winner in the field is Rich Parker, who won the Portland Open in 2003 and was last year’s runner-up at Fox Ridge.

In Monday’s pro-am, Gay fired a 7-under-par 64, while Jeff Seavey was the low pro with a 65.