DENVER -- After an abysmal road trip, the Colorado Rockies will try to regroup at home. It won't be easy since they begin a three-game series Monday with the Nationals and conclude their six-game homestand with a weekend series against the Cubs.

The Rockies were swept in three games at Philadelphia, finishing a 1-4 road trip that began with two games at Texas. In the three losses to the Phillies, the Rockies' starters combined to pitch just 11 1/3 innings. Tyler Chatwood pitched into the fourth Sunday but was dealing with the same upper back tightness that forced him out of a start in mid-June and onto the disabled list, causing him to miss two starts.

Sunday's loss was the ninth in 11 games for the Rockies, who are six games below .500 for the first time since July 22.

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Charlie Blackmon hit two homers Sunday, giving him five in the three-game series, a club record, and a career-high 20 homers, one more than he hit in 2014. Blackmon has raised his average to a season-high .324, the result of an astounding power surge. In his past nine games, Blackmon is hitting .548 (23-for-42) with three doubles, eight home runs, 14 RBIs, 15 runs scored.

"I'm seeing the ball well, but I'm not going to get too excited about it, because I know tomorrow or next week or whatever, things aren't going to go so well," said Blackmon, who is hitting .322 with nine homers at Coors Field and .326 with 11 homers on the road.

The Rockies are hoping that Monday against the Nationals, left-handed starter Jorge De La Rosa can take some stress off the bullpen with a decent outing. De La Rosa will make his 300th major league appearance and 235th start Monday. He's 2-3 with a 3.99 ERA (47 1/3 innings, 21 earned runs) in his past eight games with the Rockies 2-6 in those outings. While De La Rosa has been in those eight games, the Rockies have scored a combined 20 runs.

He was not involved in the decision in a 5-4 loss Wednesday at Texas when he gave up seven hits and three runs in five innings and left trailing 3-1. De La Rosa is 4-3 with a 5.06 ERA in 10 games, seven starts, at home this season. He's 5-1 with a 3.44 ERA in nine starts with the Rockies against the Nationals and 2-1 with a 2.53 ERA in five starts against them at Coors Field.

The Rockies and Nationals will play for the first time this season. The Nationals have played every other club in the National League. In addition to the Nationals, the Rockies have still not played Milwaukee this season.

The Nationals are embarking on a nine-game road trip that will also take them to Atlanta for four games and Baltimore for two. The Nationals' 33-24 record on the road is the second-best road record in the majors. They have won three of their past four games and eight of their past 11. At 69-47, the Nationals are a season-high 22 games above .500.

Left fielder Jayson Werth didn't play Sunday in Washington's 9-1 win over Atlanta, keeping his on-base streak on hold. Werth has reached base in a career-high 42 straight games. It's the longest on-base streak in the majors this season and one behind the club record 43-game on-base streak of Ryan Zimmerman. His streak extended from April 8-May 25, 2009.

Right fielder Bryce Harper, who had gone 9-for-67 (.134) with one homer and five RBIs since the All-Star break and missed the previous five games with a stiff neck, returned to the lineup Sunday. He went 1-for-3 with a run-scoring double on his first at-bat and two runs scored. Nationals manager Dusty Baker was going to give Harper another day off but relented when he pleaded his case to play.

Baker said, "I told him "No,' and he told me 'Please.' How do you tell a grown man (no) that says so politely that he wants to play? So, I put him back in the lineup. He actually sounded like a little kid when he said so, and you know I'm partial to kids sometimes."

Max Scherzer, who is 12-7 with a 2.80 ERA and leads the majors with 208 strikeouts, will start Monday for the Nationals. He's 1-4 with a 4.35 ERA in four career starts against the Rockies and 0-3 with a 5.32 ERA in four starts at Coors Field.

But Scherzer has been very good lately. In eight starts dating from June 29, Scherzer is 4-2 with a 1.44 ERA with 70 strikeouts and 11 walks in 56 1/3 innings. During that span, he has held opposing hitters to a .157 average and a .472 OPS.