BEIJING, China -- This one was close.

Caitlin Lowe singled home the game's first run in the ninth inning, Crystl Bustos added a three-run homer and the United States softball team escaped a tough game against Japan, 4-1 on Wednesday, to make the gold medal game at the Beijing Olympics.

The Americans were unable to solve Japanese started Yukiko Ueno until the second extra inning, when Lowe led off with a single up the middle to score Natasha Watley for a 1-0 lead.

Watley, on second base when the inning started because of the international rule, scored easily without a play at the plate and was greeted at the dugout by her teammates. Standing on first base, Lowe clapped her hands.

The run was a relief for this US softball team that hadn't lost a game at the Olympic level since 2000 -- and that is playing for its fourth straight gold medal in the sport's last appearance at the Summer Games until at least 2016.

The Americans' relief was about to turn to jubilation.

Jessica Mendoza drew a walk against a tiring Ueno, putting runners at first and second base for Bustos, the sport's premier power hitter who entered the semifinals leading the tournament with a .563 batting average and four home runs.

Bustos, crowding the plate, blasted a Ueno pitch well over the left field wall and into the bleachers to give the Americans a 4-0 lead. She was greeted at the plate by a swarm of teammates.

Whew.

"I knew she had it in her, it was only a matter of time," Lowe said of Bustos, whose three-run shot gave her nine runs batted in over just eight games at Fengtai Field.

But the Japanese still had an at-bat left, and pinch hitter Sachiko Ito led off the bottom of the ninth with a single to score Motoko Fujimoto from second base and pull her team within 4-1.

The run knocked U.S. starter Monica Abbott from the game -- it was the first earned run allowed by an American starter in eight games in Beijing -- and brought in Cat Osterman.

Osterman set down Rei Nishiyama, Eri Yamada and Satoko Mabuchi to end the game and clinch the U.S. its fourth straight berth in the Olympic gold medal match.

"With our team, it always comes down to timely hits," said U.S. catcher Stacey Nuvemen. "We were often in scoring position, but we forgot that we don't need to swing big because Yukiko (Ueno) provides the power."

The Americans have won every gold medal since the 1996 Atlanta Games -- and they're currently riding a 22-game winning streak dating back to a loss in Sydney in 2000.

They could still face tough Japan in the final game on Thursday.

The winner of the Australia-Canada game was to play Japan later on Wednesday, with the winner of that game moving on to play the U.S. in the gold medal match.