He said he heard a roar at Madison Square Garden, soon realizing that his bucket beat the point spread as gamblers moaned over the final score: Ohio State 46, Harvard 38.
"People were upset," said Swegan, whose team later lost to NYU in a consolation game. "All the gamblers were."
The year was 1946 and the NCAA tournament had only eight teams competing, with Harvard representing New England. No one could've known at the time that the school wouldn't get back until Tuesday night -- not until Penn lost at Princeton and ensured the Crimson of the Ivy League's regular-season title and automatic berth.
"I had no conception that it would be this long," said the 86-year-old Swegan when reached by ESPN.com late Tuesday night. "Isn't that something?"
The mid-1940s was quite a time for Swegan, who had celebrated Victory over Japan Day the previous summer. The Navy had started a college training program, enrolling more than 125,000 enlistees in universities nationwide, including Harvard. So the players on that 1946 team were from all over -- Swegan having come to Cambridge from Wooster College in Ohio.
"We came from different backgrounds and we pulled together to have a great team," said Swegan, who joined a Crimson program that was 4-25 the previous two seasons.
Swegan came to Harvard to play three sports. He played hoops. He played baseball. And he said he even played football with Bobby Kennedy.
After that '46 NCAA tournament, he stayed to watch the NIT in New York and said he stood next to Babe Ruth in the back row at the old Madison Square Garden, watching the more prestigious NIT championship. He said he's still mad at himself for not asking for his autograph.
Swegan left Harvard after one year, going back to Wooster. He stayed in athletics, serving as an assistant at Penn State and coaching for 17 years at various schools.
He lived his life, had children, grandchildren, lost his first wife, got married again to his current wife Mary seven years ago. He settled back in Ohio -- in Sebring, near Youngstown.
But all along, he's followed Harvard hoops, wondering if they would ever recapture the magic of that one season so many decades ago.
A year ago, he thought it was finally going to happen. Harvard was about to play Princeton for the Ivy League championship and so he reached out to head coach Tommy Amaker.
"I decided to give him a call and wish him well," Swegan said. But then Princeton beat Harvard on a last-second shot and the Crimson's hopes of an NCAA berth were dashed.
But the core of the team returned and Harvard was picked as the Ivy favorite, was ranked for a number of weeks and finished the regular season with a weekend sweep at Columbia and Cornell.
So this week, Amaker called Swegan, as Harvard waited to see if Penn would lose at Princeton and allow the Crimson to get back to the NCAA tournament, preventing another one-game playoff.
"We had a nice chat," Swegan said.
On Tuesday night, Don and Mary Swegan were glued to ESPNU, waiting for updates, seeing what what would happen with Penn and Princeton.
And then he saw the result. It was over. Princeton won. Harvard had won the Ivy League automatic berth.
Sixty-six years after he joined a collection of Navy ROTC members to lead Harvard to the NCAAs, the Crimson were finally returning.
Swegan said he's not sure who has survived from the '46 team. He knows at least three or four have died.
Swegan said he would love to find a way to be at Harvard's first tourney game and is hoping the Crimson get placed in Columbus. He can't commit to traveling too far, but wants to attend. He lived to see this day, and he wants to see the Crimson finally play in the tournament that he so fondly remembers from his youth.
"I have wondered for a long time if this would happen," said Swegan. "It has brought me a lot closer to Harvard the last two years. I hadn't had much contact for a long time. I didn't graduate there. But Tommy's success with the team has gotten me reconnected. I'm quite excited about the possibilities and so pleased that they're doing well. It's a great thing. I hope I can be there."
Swegan has waited six-plus decades for this day. No other former player of any other NCAA tournament-bound team probably deserves to be in attendance more than Swegan and any other possible surviving teammates.
"I had no conception that it would take this long," he said. "It sure is something."