SAN DIEGO -- Jason Marquis almost was forced out of the game in the sixth inning again -- albeit for a much different reason.

This time, he stayed on the mound and led Washington to the victory.

Marquis threw six strong innings to help the Nationals beat the San Diego Padres 2-1 on Friday night.

Michael Morse hit a two-run homer in the second inning and Marquis was cruising before the Padres rallied in the sixth. Ryan Ludwick walked with the bases loaded to force in a run, but Marquis responded by striking out highly touted rookie Anthony Rizzo on a nasty full-count changeup and getting Jorge Cantu to bounce out to end the inning.

"We call those man pitches," Nationals closer Drew Storen said. "You've got to man up there, and he did. He made that man pitch, and it was fun to watch."

Rizzo made his major league debut Thursday night after being promoted from Triple-A Tucson. But it's doubtful that the 21-year-old Rizzo saw many pitches in the minors like the ones he saw in the sixth.

"I feel confident in all my pitches right now," Marquis said. "I've been working hard to be able to throw them in any count. I wasn't giving in, in that situation. I didn't want to leave one out over the plate with the power he's shown in Triple-A and the pitch he hit off Livan."

Rizzo hammered a tripled off the center-field fence against Livan Hernandez in his debut, missing a homer by a few feet. But Marquis got the rookie this time.

"He threw a great pitch there, a great changeup," Rizzo said. "My heart was racing a little bit. I tried to slow it down. It was a good at-bat, but it was a pitcher's pitch that I couldn't do anything with."

Marquis (7-2) picked up right where he left off last Sunday at Arizona when he shut out the Diamondbacks through 5 1/3 innings before he was ejected for hitting Justin Upton with a pitch.

He was suspended for five games and fined an undisclosed amount. But he appealed and is able to pitch until there is a decision.

Marquis held the Padres without a hit until Ludwick's leadoff double in the fifth. The right-hander allowed one run and three hits, struck out five and walked three.

Morse staked Marquis to a lead with a drive off Mat Latos (4-7) for his 10th homer. Lance Nix led off with single, then Morse hit a 1-2 fastball into the left-field seats.

Morse has homered eight times in his last 18 games.

Tyler Clippard pitched two hitless innings and Storen worked the ninth for his 13th save in 14 chances to complete the four-hitter.

Washington had four hits, two coming after Morse's homer.

The Padres loaded the bases in the sixth on Chris Denorfia's one-out double, a single by Jason Bartlett and a walk to Brad Hawpe. Ludwick drew a full-count walk to bring home San Diego's only run.

"He got really tested in the sixth inning, that was tough," Nationals manager Jim Riggleman said of Marquis. "Baserunners all over the place, a lot of pitches, a very stressful inning. But to come out of it with one run, that's good veteran pitching right there."

Rizzo walked twice and was hit by a pitch, finishing 0 for 1 with a strikeout. The first baseman committed an error in the ninth inning on a ground ball.

Latos, who won his previous three starts, gave up two runs and four hits in six innings.

San Diego, which had won nine of 13 games, dropped to an NL-worst 14-24 at home. The Nationals won for just the third time in eight games.

Game notes
Washington RHP Stephen Strasburg, last year's rookie sensation, threw a bullpen session. Strasburg, a San Diego native who attended San Diego State, is on the mend from right elbow surgery in September. "Where he's at is nine months into a 12-to-18 month (rehab) process," Riggleman said. ... San Diego signed first-round draft pick Cory Spangenberg. The 20-year-old Spangenberg was the 10th overall pick and became the first first-rounder to sign. ... The Nationals placed RHP Cole Kimball (shoulder inflammation) on the 15-day disabled list. RHP Ryan Mattheus was brought up from Triple-A Syracuse.