Obama made a surprise trip to the Nationals' stadium in Southeast D.C. to kick off Father's Day weekend and watch Strasburg, a sensation in Washington and the world of sports, make his third career start.
The president, daughters Sasha and Malia and brother-in-law Conrad Ng arrived at the stadium with an entourage that included White House senior adviser David Axelrod.
Flashbulbs began popping along the third base side as fans realized the president there.
Obama, wearing a white short-sleeved shirt and a White Sox cap, sat in a private box a few levels up behind home plate. He was seen sipping a beer, laughing and pointing out to his daughters things happenings on the field. Sen. Kent Conrad, D-N.D., was also spotted in the box.
The game was sold out and the evening was warm, sunny and pleasantly non-muggy for Washington in June.
Obama last visited the park to throw out the first pitch at the Nats' home opener in April. He surprised the crowd then by donning a White Sox hat just before sailing out a high, wide toss.