MINNEAPOLIS -- Nationals left-hander John Lannan found himself in a pitchers' duel with Twins right-hander Livan Hernandez on Tuesday night.

When it was over, it was Hernandez who won the battle as Minnesota defeated Washington, 2-1, at the Hubert H. Humphrey Metrodome. The game lasted just one hour and 59 minutes. It was one of the shortest games involving the Nationals this season.

The loss breaks the Nationals' modest three-game winning streak.

It looked like Lannan was going to have one of his best outings. He didn't allow a hit until the fourth inning -- a double by Joe Mauer. Lannan was cruising, in fact, until the sixth inning.

After getting two quick outs in that inning, Lannan's breaking balls betrayed him. On a 2-2 slider, he gave up a single to Mauer. The next hitter was Justin Morneau, who took the first pitch he saw -- a curveball -- and hit a two-run homer. The ball landed in the right-field upper deck.

According to manager Manny Acta, there is nothing in the scouting report that said to throw Morneau a curveball to get him out. But Lannan thought that since he was able to induce Morneau to hit into a double play on the same pitch, why not try it again.

"It was a curveball, up, and he hit it a long way," Lannan said. "It was a mistake that ended up costing me. I threw a good one to him in his first at-bat. I figured if I threw the same kind of pitch ... I shouldn't have thrown that pitch in that same situation. It was a mistake."

Despite the mistake, Lannan ended up throwing his 10th quality start of the season, which left Acta pleased. In those quality starts, Lannan is 4-4 with two no-decisions.

"I can't control wins and losses," Lannan said. "We just swept Seattle, so I'm happy about that, but I just have to keep on battling. I just have to keep on going."

Lannan was given a 1-0 lead in the top of third inning, when Cristian Guzman's infield single drove in Paul Lo Duca.

Lannan lasted seven innings and gave up two runs on five hits.

Morneau and Mauer came away impressed with Lannan.

"He mixed it up," Morneau said. "He hit his spots. He kept us off balance. We were probably a little overly aggressive."

Said Mauer, "His ball kind of gets on you. I don't know if it's something with his delivery. He had a good angle on his pitches. He had some good stuff working tonight."

Hernandez was in vintage form on Tuesday night. He looked like the ace that won 15 games for the Expos in 2003. The Nationals were overly aggressive and had a tough time hitting his breaking pitches.

Unlike his days with the Nationals and Expos, Hernandez didn't throw a lot of pitches. He threw only 77 pitches and 50 of them went for strikes.

"The sinker was very important. That was the way I have to pitch, because I have to trust my sinker," Hernandez said. "I was running a little bit out of gas. I don't want to go back and try to be a hero. The more important thing is to try and win games. We have maybe the best bullpen in baseball now. You have to trust the guys."

Acta was a third-base coach with the Expos when Hernandez was at his best. Acta indicated that Hernandez was able to throw strike one often again the Nationals.

"Usually, he pitches behind, prays on hitters' aggressiveness and make them chase when the hitters are ahead in the count," Acta said. "Tonight, he threw strike one and we got overly aggressive. He knows how to do that. He took advantage of our guys. He had very few pitches for seven innings."