Perez badly wanted to beat the Dodgers, but he lasted four innings and gave up the six runs on eight hits. He found himself in trouble in the first inning. Matt Kemp hit a two-run homer, and Nomar Garciaparra drove in Russell Martin with a sacrifice fly to center fielder Lastings Milledge.
In the fourth inning, Garciaparra led off and homered, and Angel Berroa and pitcher Derek Lowe had RBI hits.
Perez said none of his pitches were working. He had a great bullpen session, but by the time he hit the mound in the first inning, he knew he was in for trouble.
"I was too anxious," Perez said. "I wanted to come beat them, be out there as long as I could and pitch a good game. I found out I didn't have my best stuff. I feel bad because I want to come to Dodger Stadium and show that [how I won a lot of games] in this stadium. Today, I didn't have my good stuff."
Although he wanted to beat the Dodgers, Perez said he doesn't have any bitterness toward them. He likes the team they put together and feels they have a chance to win the National League West title.
"They have a good team. They have great talented young guys. If they keep playing that way, they might win the division," he said.
Perez may have pitched his last game as a member of the Nationals. The Trade Deadline is on Thursday, and the Nationals would like to get prospects in return.
"I don't think about it," Perez said referring to the possibility of getting traded. "Whatever is going to happen is going to happen. If I get traded, I get traded. If I don't get traded, I'm happy here."
Perez's former teammate, Lowe, was brilliant on the mound. The right-hander pitched eight shutout innings and gave up only one hit. He struck out four and walked one. It helped that Lowe threw first-pitch strikes to the Nationals' hitters most of the night.
Manager Manny Acta often talks about how the Nationals are young and inexperienced, but the truth is, five of their players --- Ronnie Belliard, Willie Harris, Austin Kearns, Paul Lo Duca and Felipe Lopez -- in the starting lineup on Saturday are either in their late 20s or are already in their 30s. None of them had a chance against Lowe.
In fact, Harris went so far to say that Lowe looked like the Red Sox pitcher who threw a no-hitter against the Rays back in 2002.
"I faced him in the past and he had his Boston stuff," said Harris, who went 1-for-4 in the game. "That ball was bouncing all over the place and it was just tough to get to a hitter's count because he was 0-1 to you right away. For me, I have to take pitches and try to work him over. But he was ahead of me all night. We weren't able to get those 2-0, 2-1 counts.
"It was one of those games where he just beat us. He just flat out beat us. He had all of his stuff working. He had it tonight."
The Nationals have lost five straight games, dropped to 38-66 and are 0-5 during this current West Coast swing.
"It's upsetting. I think we should have won at least two games in San Francisco, but we came up short," Harris said. "It's always the same old, same old. We are coming up short. It's time for us to start winning those one-run games instead of coming up on the other end of those one-run games. Hopefully, things can turn around quick."