Excellent starting pitching has helped the Miami Marlins stay relevant in the NL wild-card hunt.
Miami (61-62) has won six of nine after dropping six of eight and can reach the .500 mark for the first time since July 29. They're 3 1/2 games out of the league's second wild-card spot following Saturday's 2-1 win.
Henderson Alvarez completed seven strong innings in his first start after missing two due to shoulder inflammation, lowering the Marlins' ERA to 2.89 over the last nine games.
"I'm just thankful that everything went well today and I was able to go out there and help my team," Alvarez said. "We're in the middle of the (playoff) hunt so this is an important stretch for us."
Koehler (8-9, 3.86 ERA) hasn't been much of an asset lately for Miami's staff. He owns a 4.85 ERA over his last seven starts, though he got the win in a 6-5 victory over St. Louis on Monday, allowing three runs in five-plus innings.
The right-hander has lost two career matchups with Arizona and endured a particularly tough time in a 9-1 road loss on July 7, surrendering a season high-matching seven runs in just three innings - the shortest start of his career.
Arizona (53-70) committed five errors Saturday, its most since being charged with six in a 14-1 loss to the Los Angeles Dodgers on July 3, 2010. The Diamondbacks' 91 errors are the most in the NL and their .981 fielding percentage marks the franchise's lowest since also finishing with a .981 mark in 2008.
"Through all the mistakes we battled and we only gave up two runs, one unearned and one earned," manager Kirk Gibson said.
Regardless of the poor defense, Arizona's offense was ineffective again, recording six hits for the third straight contest. Mark Trumbo's first-inning sacrifice fly providing the only run for the Diamondbacks, who are averaging 2.3 runs and batting .184 while dropping four of six.
Aaron Hill and Miguel Montero are a combined 5 for 32 in that stretch while David Peralta is just 2 for 27.
However, Sunday might provide a good chance for Peralta to snap out of his slump as he was 2 for 2 against Koehler with a double and triple in last month's encounter.
For all of Arizona's offensive struggles, Ender Inciarte was 2 for 4 Saturday to extend his hitting streak to 15 games. He's batting .318 during the streak.
Josh Collmenter (8-6, 4.09) was on the mound Tuesday at Cleveland but the game was called in the top of the fourth due to rain. Prior to that, he gave up three runs in six innings of a 4-3 loss to Kansas City on Aug. 6.
Collmenter has struggled on the road, going 2-3 with a 6.12 ERA in eight starts while allowing five-plus runs in three of the last four.
He did fare well in a 4-3, 10-inning victory over the Marlins on July 9, holding Miami to one run over seven innings.