Ankiel singled in the third inning and homered in the fifth off Mike O'Brien in the Houston Astros' 7-6 win over a New York Yankees' split squad on Thursday.
The 33-year-old ex-pitcher is 6 for 9 with a double, triple and home run.
"I'm sure I'll have dips," Ankiel said. "I don't think I can keep at the pace I'm going, but it's really not about that. What I'm looking for is trying to see the ball and get good pitches to hit. The results you can't control, but I can control which pitches I swing at."
Ankiel hit .228 in 68 games and 158 at-bats with the Washington Nationals last season.
"It feels great," he said. "I feel like I'm seeing it great right now, for where we're at, and I just hope to continue on the path we're on and get better each day."
Ankiel agreed in January to a minor league contract. If he's added to the 40-man roster, he would get a $750,000, one-year deal and the chance to earn $775,000 more based on plate appearances.
"He's off to a tremendous start. He's a pro's pro," new Astros manager Bo Porter said. "He's going to be a great teammate. He's going to add veteran leadership in the clubhouse, and he's an outfielder who can change the game with one swing, and he can pay all three outfield positions."
Ankiel would rather be on this kind of roll a month from now.
"Later in camp I think you'll start seeing more cutters and breaking stuff," he said. "It might be just as important to get at bats later on as it is now. Really just being able to hit the heater right now is what I'm working on, and the adjusting will come later."
Brandon Laird followed Ankiel's home run an inning later with a grand slam off loser Shane Greene.
Harrell was efficient in his second spring start, giving up three singles and getting two double plays.
The 28-year-old right-hander is coming off a season in which he went 11-11 in 32 starts, no small achievement on a team that lost 107 games.
"I look at it as I pitched in 30-something games last year and I think we won 18 of my starts," he said. "More important then getting the win is the team gets the win, and I give them a chance to win, keep the game close. If I get a win it's just the cherry-on-top type of thing."
Sam Demel got the win for the Astros.
The 22-year-old Marshall pitched to the minimum nine batters in his three innings, striking out three while Francisco Cervelli threw out two runners attempting to steal.