WASHINGTON -- Right-hander John Patterson had another solid outing, and the Nationals defeated the Phillies, 3-1, in front of 23,332 fans at RFK Stadium on Tuesday night.

Patterson pitched 6 2/3 innings, and gave up just one run on six hits. He struck out six and walked four. In total, Patterson threw 113 pitches, 67 of them for strikes.

Patterson got off to a slow start, giving up an RBI single to Jim Thome in the first inning, but he made adjustments and prevented the Phillies from scoring during his time on the mound.

"The Phillies were laying off my offspeed stuff and were just looking for the fastball early in the game. They were just jumping on my fastball early in the count," said Patterson. "I had to slow them down a little bit and start working my fastball in there."

Patterson is now 2-1, with a 0.98 ERA. His performance of late hasn't surprised manager Frank Robinson, who saw a glimpse of Patterson's potential before the pitcher tore his groin last April.

"This is what we thought he would do after we got him in a trade with the Diamondbacks," said Robinson. "Now he's putting it together, and we are reaping the benefits of it. I'm very happy that he's here with us.

"If you believe in your stuff, then you can get by like he did tonight. That should assure him that you don't always have to have your best stuff to win or keep your team in the ballgame."

The Phillies' biggest chance to score came in the seventh inning. They had runners on first and second with two out, and Jim Thome coming to the plate. Robinson decided to take Patterson out of the game and bring in right-hander Gary Majewski instead of left-hander Joey Eischen. Robinson decided to give Eischen the day off, as Eischen had pitched four consecutive games.

Majewski came through, inducing Thome to ground out to second to end the inning. Left-handed hitters are now 0-for-8 against Majewski.

"I thought Gary was fresh, and I like his fastball and sinker. He threw the ball in a good spot. That's what we needed in that situation," said Robinson.

Said a grateful Patterson: "I was expecting to see Eischen come flying out of the bullpen, but [Majewski] came in and did a great job to get Thome, who is their RBI guy. It was perfect."

Majewski, too, expected Eischen to get the call, and admitted that he was nervous when he reached the mound.

"I was happy that Frank wanted me in that situation with runners on," said Majewski. "I've been doing good and throwing strikes. He said I could come into these situations and get it done, and tonight I did."

Phillies right-hander Jon Lieber, Patterson's counterpart, lasted six innings, giving up three runs on four hits.

The Nationals' first run was scored in the first, when Nick Johnson hit a 1-0 pitch over the right-center-field wall for his first home run of the season. The hit extended his hitting streak to 16 games.

"It was a fastball -- middle in. I was trying to get on base and hit the ball hard. The ball went out of the park, and I took off running," said Johnson.

Johnson would later leave the game with a contusion on the back of his right leg, and is listed as day-to-day. He hurt the leg when he fouled off a pitch in the third inning. He is not expected to play on Wednesday afternoon against the Phillies.

The Nationals took the lead in the fifth inning. With one out, Patterson doubled near the right-field line. The next hitter, Brad Wilkerson, hit a two-run home run into the right-field upper deck -- a shot that hit above the 470-foot sign -- to give the Nationals the two-run lead.

It was the first multi-homer game at RFK this season.

"Lieber's strength is the cutter. He was trying to keep me off the outside part of the plate," said Wilkerson. "He started me inside, and I got a fastball in and hit the home run. It felt really good to jump ahead, because Patterson threw a great game for us.

"I was hoping that the ball would stay fair. I knew it had the distance, but I really didn't see where it ended up. I was trying to run the bases and enjoy the trot."

Majewski, Luis Ayala and Chad Cordero shut out the Phillies the rest of the way, with Cordero picking up his fourth save of the season.

The Nationals improved their record to 11-10, and the Phillies have fallen to 9-12.