PHOENIX -- Alex Romero has made a quick adjustment to starting every day in the Major Leagues.

Called up from Triple-A Tucson on July 4 after outfielder Eric Byrnes was put on the disabled list for a strained hamstring, Romero is now the regular starter in right field with Justin Upton also on the disabled list with a strained left oblique.

Romero has started five games since Upton injured himself July 9 and has strung together a career-high five-game hitting streak after he doubled down the line in Saturday's game at Chase Field.

D-backs manager Bob Melvin has been impressed with the rookie's approach at the plate as well as in the field. Melvin said that during batting practice, Romero goes for fly balls at full speed.

"He works very hard on his defense, as hard as anyone I've been around," Melvin said. "He's a good defensive outfielder. Being that we have injuries to our two corner outfielders, we have Conor [Jackson] playing a little bit out of position and is still kind of getting used to the position, and to have another guy that's a true outfielder that knows how to play the position well defensively helps out."

In Friday night's game against the Dodgers, the 24-year-old from Maracaibo, Venezuela, made a running grab as he glided toward the first-base line, robbing an extra-base hit. It was a play that Melvin said he didn't think Upton could have made in right field.

Through 18 games (10 starts), Romero has been flawless in the outfield, owning a perfect fielding percentage.

"He's done a nice job for us," Melvin said. "His preparation is what allows him to feel comfortable in games. Anytime a guy gets a taste [of the Majors] for the first time there's some trepidation and some insecurity that goes along with it, but I think the way he prepares goes towards him feeling comfortable out there when he gets some starts, whether its in right or left or whenever he has to come into the game."

Romero is just relishing the role for the time being, but has taken complete advantage of his extended playing time.

"It feels good when you play every day," Romero said. "I'd say I've done pretty good so far. When you play every day you get a chance to make adjustments. It's a lot easier when you play regularly than when you only get one at-bat a day."