Volquez (2-0), who struck out five and walked three, has won both starts since he was called up from Triple-A Oklahoma on Sept. 1. He was demoted to Class A Bakersfield at the start of the season in an effort by Rangers management to get more maturity from one of the organization's top prospects.
"The kid is showing he can pitch at the major league level," Rangers manager Ron Washington said. "I don't see any pitch that he can't throw for strikes."
During the season, Volquez advanced to Double-A Frisco and Oklahoma, compiling a combined 14-2 record at those stops to earn another shot with the Rangers. This was his 13th big league start over three years, and he might have pitched even deeper into Friday night's game if not for a blister on his right thumb.
"They took me out to save me for my next start," Volquez said. "I'm pitching better than last year because everything was going so fast for me last year. This year I know what I'm doing and I'm just concentrating on making my pitches."
Catalanotto led off the first with a home run and had three hits, needing only a double for a cycle.
But Washington pinch hit Sammy Sosa for Catalanotto in the eighth, hoping for some power. Sosa grounded out.
"I thought I'd get one more at bat," Catalanotto said. "You really don't get that many opportunities to go for a cycle. I'm a bit disappointed, but maybe down the road there will be another opportunity. Our team won the game that's what is important."
Said Washington: "I was only concerned about winning the ballgame."
Texas opened a three-game series against Oakland, pulling within two games of the third-place A's in the AL West. The Rangers, who've been in last place since April 25, have finished third the last three seasons.
Oakland has lost nine of its last 13.
Dan Haren (14-7) allowed 15 runners in 4 2/3 innings, giving up five runs and 12 hits. Haren, who threw 100 pitches, has won once in his last seven starts.
Haren still leads the AL with a 3.03 ERA, but that was little consolation.
"I didn't have much and it looked like it," Haren said. "And it's hard when you're not playing for anything. Maybe that's part of it. When you're going good it's easy. This is when you earn your money."
Haren was in trouble from the outset, allowing Catalanotto's 10th homer of the season on his second pitch of the game.
"I was just trying to get ahead and he jumped on it," Haren said. "He's a good, quality hitter."
Texas made it 4-0 with a three-run fourth on Ramon Vazquez's RBI double, Catalanotto's run-scoring triple, and Michael Young's RBI single.
In the fifth, Hank Blalock tripled and Catalanotto delivered a two-out RBI single, knocking out Haren.
Oakland avoided its ninth shutout of the season with a two-run eighth. Jack Cust had a sacrifice fly off Wilson, and a run scored on Young's fielding error at shortstop.
- Catalanotto led off the first with a homer for the third time this season and eighth of his career.
- Oakland is 6-7 against Texas this season.
- Haren struck out seven and walked three.
- The A's haven't committed an error in nine straight games, a season-best streak.
- Haren had his shortest outing since going 4 2/3 innings against Cleveland on Sept. 18, 2006. The 12 hits allowed tied a career-high. He also gave up 12 hits to Cleveland on July 27, 2005.