Playing first base and batting fourth for Team USA, Brown drove in three runs with a pair of singles in an 8-7 loss to Korea. His dramatic, two-out, two-strike single to left-center drove in the tying and go-ahead runs in the top of the ninth, but the Americans let it get away in the bottom half of the inning.
A natural third baseman still learning the finer points at first, Brown, 26, had the misfortune of factoring in a key play during Korea's winning rally. The score was tied at 7 with a runner at first and one out when reliever Jeff Stevens uncorked a pickoff throw past an unsuspecting Brown, sending Taekkeun Lee to third.
Lee scored the winning run on a sacrifice fly, bringing disappointment on what was shaping up as the biggest day of Brown's career. He'd delivered in the clutch against Korean right-hander Suk Min after fouling off three pitches with an 0-2 count.
Asked about the errant pickoff throw setting up the decisive run, Team USA manager Davey Johnson explained that Brown was attempting to communicate his positioning with the bench when Stevens misread his gesture.
"Matt was motioning to the bench," Johnson said. "He wanted to be a little off the bag. Jeff thought he was looking at him."
Kevin Jepsen, a 24-year-old right-hander and teammate of Brown's at Salt Lake, would have been in line for the win if the Americans had held the ninth-inning lead. Jepsen held Korea scoreless in an impressive eighth-inning effort.
Angels manager Mike Scioscia, en route to Angel Stadium for Wednesday night's game against the Mariners, wasn't able to watch the game in Beijing on television but got glowing reports on Brown and Jepsen.
"It's a great environment to be in for a young player," Scioscia said. "There's a lot of growth with the competition. That's why we really like winter ball. It's as competitive as anything you'll see in the Major Leagues."
Brown is hitting .326 at Salt Lake with 21 homers and 67 RBIs in 93 games -- 39 at first, sharing time with Kendry Morales and Freddy Sandoval, and 31 at third, dividing time there with Sandoval and Brandon Wood.
Jepsen is 1-3 with a 2.53 ERA and two saves in 13 games at Salt Lake. He was promoted from Double-A Arkansas, where he was 2-1 with a 1.42 ERA and 11 saves.
It was Korea's first win over Team USA in six Olympics games, putting the Americans in an early hole. The field of eight will be reduced to four by records after each team faces each of the other seven nations once. Medal games are set for Aug. 23 after semifinal games are played on Aug. 22.
Three-time Olympic champion Cuba faces Team USA, the 2000 Olympic champion, on Thursday.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.