Pitcher Micah Owings' pinch-hit homer tied the game in the sixth and the Arizona Diamondbacks rallied from four runs down to beat the Houston Astros 8-7 on Wednesday.

Owings, 4-0 as a starter and arguably the best-hitting pitcher in the game, hit the first pitch of the game from reliever Dave Borkowski to the opposite field seats, a two-run shot with two outs that tied it at 7-7.

Chris Young followed with a double, then scored the go-ahead run on Eric Byrnes' single.

Arizona (20-8) became the season's first 20-game winner, a franchise record 19 of them in April. Arizona won its eighth series out the last nine. The exception was a split of a two-game set with the Los Angeles Dodgers.

The Diamondbacks' lone series loss came in the season opening games at Cincinnati to open the season.

The Astros led 6-2 after two innings against Randy Johnson. Houston scored four in the first, three on Carlos Lee's sixth home run of the season.

Johnson, in his fourth start of the season after rehabilitating from his second back surgery in two years, allowed six runs on nine hits in four innings. He struck out two. Brandon Medders (1-0) gave up an unearned run in two innings to get the victory.

Chad Qualls, Tony Pena and Brandon Lyon each threw a scoreless inning to wrap up the victory. Lyon earned his ninth save in 11 tries.

Lyon gave up a single to Kazuo Matsui and a one-out walk to Lance Berkman, but Lee and Jose Cruz Jr. flew out to center to end the game.

Arizona's comeback started with Jackson's solo home run off starter Shawn Chacon to cut it to 6-3 in the third. The Diamondbacks scored two in the fourth to cut it to 6-5, including an RBI double by pinch-hitter Jeff Salazar.

Chacon, in his shortest outing of the season, allowed five runs on seven hits. He struck out seven and walked one.

Houston made it 7-5 in the sixth when Medders walked pinch-hitter Darin Erstad. Erstad took third when shortstop Stephen Drew muffed Hunter Pence's grounder. Pence scored on Matsui's sacrifice fly.

Drew started the Diamondbacks' three-run sixth with a double to left-center. After two outs, manager Bob Melvin sent Owings to the plate, and Borkowski came on in relief.

Owings hit his first pinch-hit home run of his two-year major league career. He is scheduled to start Friday night against the New York Mets.

Notes:@ Max Scherzer, who retired all 13 batters he faced _ striking out seven _ in his major league debut on Tuesday, will start Monday at Philadelphia. ... Houston has lost seven of eight at Arizona. ... Chacon, who entered the game with a 2.45 ERA, has no decisions in six starts.