Phoenix, AZ (Sports Network) - Randy Johnson was stellar on the hill to pick up career win number 291, and the Arizona Diamondbacks edged the Chicago Cubs, 2-0, in the opener of a three-game set.

Johnson (7-7) allowed just two hits over seven innings while striking out four and walking one to move to 13-0 lifetime against the Cubs. Chad Qualls worked out of trouble in the ninth to pick up his second save of the season.

Alex Romero hit a solo home run and Stephen Drew had an RBI triple, the only two hits for Arizona, which has only three wins in its last seven contests.

Rich Harden (0-1) was the hard-luck loser as he allowed just one hit -- the Romero home run -- while fanning 10 and walking just two batters in his second start for Chicago. The right-hander, who was acquired from Oakland along with swingman Chad Gaudin on July 8, has allowed just one run in 12 1/3 innings of work since the trade.

"Randy pitched a great game," Harden said. "I made one bad pitch, a two-strike changeup right down the middle. I felt good out there but a little bit inconsistent."

Reed Johnson and Jim Edmonds accounted for the only Chicago hits, as the Cubs dropped their fourth contest in the last five games.

Chad Tracy broke up Harden's perfect game bid as he worked a walk to lead off the fifth inning. Though, he was left stranded as Mark Reynolds went down swinging, Chris Young flied out and Chris Snyder grounded out to end the inning.

Romero deposited a Harden slider over the fence in right field, the first home run of his career, to give Arizona a 1-0 lead in the sixth.

The clubs combined for three hits through seven innings.

"We had to play defense tonight," Arizona manager Bob Melvin said. "It had to be a clean game with both pitchers, it looked like after two or three innings that it would be tough to score. That is when the other facets of the game come into play."

Bob Howry took over for Harden in the home eighth and gave a leadoff free pass to Snyder. Romero flied out, as did pinch-hitter Tony Clark, but Drew smoked an RBI triple off the wall in right to make it a 2-0 game.

Qualls was on the hill for Arizona in the ninth and walked leadoff man Ryan Theriot. Pinch-hitter Kosuke Fukudome then hit a slow-roller towards first and beat Qualls to the base to make it first and second with no outs. Derrek Lee, however, grounded into a double play, moving Theriot to third. Aramis Ramirez then grounded out to end the game.