With a catch of 18-4 Friday for a two-day total of 30-9, the pro from Bixby, Okla., kept two South Carolina challengers at bay, but just barely. Eight ounces back was Casey Ashley of Donalds, S.C., who put up 30-1 for two days. A home-lake favorite, Davy Hite of Ninety Six, S.C., fell one spot into third with 29-7 after two days.
Fourth and fifth places were secured by pros from Missouri: Brian Snowden with 28-5, and Rick Clunn with 27-12.
Dustin Wilks moved into the third day of competition in 15th with 25-8.
Complete standings can be found at Bassmaster.com.
Roumbanis struggled on the first day, but was able to turn it around and establish a pattern he said is strong enough to carry him to a repeat win. He encountered a slight hitch: The pattern drew strikes from stripers, too.
"It was a little slow because I started catching striped bass. Every time I'd hook a fish, I'd say, 'Please be a bass, please be a bass.'"
But after about two hours of fishing, the fish he was hooking into began to be largemouth. The action picked up speed, and it was success for the remainder of the day.
"I caught a good 15-pound bag in an hour," he said. "And then it really picked up even more."
He said his pattern held from spot to spot, producing a fish every time he put the trolling motor down.
At one point in the day, he tried to catch a fish that wrapped a tree and broke off the first day. He made up for it Friday by patiently playing a 4-pounder that was wrapped in a tree in deep water, probably a Christmas tree someone planted as a fish attractor, he said.
"I hooked it and could feel it getting stuck in something. I could look down and see the tree. I held there for 15 minutes, going back and forth on the trolling motor to make it move just a little each time. I knew it was a big one."
The bass popped free from the tree branch, and Roumbanis reeled it in. Added to a 5-5 earlier, he was pumped for the day.
"It's so much easier when you can catch a couple big ones from the get-go," said Roumbanis, whose 2008 win on Murray was his most recent Bassmaster win, and first Elite-level victory.
South Carolina native Ashley climbed from seventh place to take the runner-up position. His second-day bag was 15-4, not too off from his first-day catch of 14-13, but it carried him past others who were not as consistent.
Ashley keyed on the early morning blueback herring bite.
"I got a big bite this morning," he said. "I watched that fish come up, blowing bait on a point, five times yesterday, but I couldn't get her to bite. This morning, I pulled in there and pretty much just waited for it to come up."
Ashley patiently waited five minutes, and the fish hit the bait as soon as it hit the water on the first cast. He said he could see other fish on the same spot, but he could not get them to bite.
"These banks have been beat by everybody throwing topwaters, everybody throwing flukes," he said. "The fish are still there, they are just very educated."
Hite, who lived in Prosperity before moving to the nearby town of Ninety Six, fell one place Friday with 13-0, not as good as his first day of 16-7. He's confident he can move back up.
"I missed a couple opportunities," he said. "You don't get many opportunities for good quality fish, and yesterday I capitalized on the ones that bit, today I didn't."
He said the bass are "hook-shy" due to pressure and don't commit to the bait, so it's easy to lose one.
Friday's biggest bass, a 5-9, was by Dean Rojas, the winner of April's TroKar Battle on the Bayou in Louisiana. Thursday's biggest bass of 6-9 brought in by Day One leader Jami Fralick still holds the lead in the Berkley Big Bass of Tournament competition for a $500 bonus.
The competition for $100,000 and an instant entry into the 2012 Bassmaster Classic will continue Saturday with the top 50 finishers from Friday. The field will cut to the top 12 for Sunday's competition.
Free and open to the public, the 3 p.m. ET weigh-ins will be at Dreher Island State Recreation Area on Lake Murray.