PHOENIX (AP) - The first home run felt so good, Shawon Dunston decided to try for another. Dunston hit a grand slam in the sixth inning, then was ejected in the eighth after trying to stretch a triple into an inside-the-park homer as the St. Louis Cardinals beat the Arizona Diamondbacks 6-1 Tuesday night. "I wasn't trying for a home run," Dunston said about his slam, the fourth of his career and his fourth homer this year. "I'm not a home run hitter. I just try to hit the ball hard and play hard and make something happen." Rick Ankiel (5-2) didn't allow a hit until Arizona starter Omar Daal reached on a bunt single with no outs in the sixth. "I think my mechanics are getting better, and consequently for me to stay in control and throw strikes, things are going good, "said Ankiel, who leads NL rookies in wins, strikeouts (56) and ERA(3.70). Mike Matheny put the Cardinals ahead with a sacrifice fly in the fifth, and Dunston homered in the sixth after a two-out double by Jim Edmonds, an intentional walk to Mark McGwire and an infield hitby Eric Davis. Dunston followed with a 372-foot drive to left. He tripled over the head of center fielder Steve Finley in the eighth, but was thrown out at home by shortstop Tony Womack when he tried to stretch it into an inside-the-park homer. Dunston argued with first-base umpire Greg Gibson, who slid down the line to make the call, and was ejected. Replays appeared to show that Dunston's foot was on the plate before catcher Kelly Stinnett applied the tag. "I didn't say anything obscene. I just told him I thought I was safe," Dunston said. "I saw it on the monitor and I still think I was safe.