SURPRISE, Ariz. -- He didn't start the Arizona Fall League Fall Stars Game on Saturday, but he sure left his mark on it.

Outfield prospect Stefen Romero, ranked No. 7 on the Mariners' Top 20 Prospects list, didn't enter the game until the sixth inning as a defensive replacement in left field for Astros outfield prospect Delino DeShields Jr.

Romero didn't waste any time making his presence felt. He took the first pitch he saw from Rays farmhand Mike Montgomery the other way with Eddie Rosario aboard for a two-run homer to give his West Division squad a 6-0 lead.

"I was just trying square the ball up," said Romero, who helped the West beat the East, 9-2. "Coming in, I knew we were up early. I felt like they were going to try to get ahead of me early. Luckily, my first at-bat, I jumped on a fastball right away up in the zone. Luckily, it went out, a wall-scraper. Second at-bat, I just wanted to be a little more patient. Fortunately, he got a slider up and I did the same thing."

That second opposite-field home run came when he led off the eighth against Tigers pitching prospect Corey Knebel, giving Romero a 2-for-2 night with three RBIs. That's hard enough to do in any game, but even tougher when the first five innings are spent watching from the bench. Romero was able to use some past experience to help him get ready for the situation.

"I had some similar experience in big league camp, coming in the sixth, seventh inning, so I tried to prepare myself the same way I did in big league camp," Romero said.

Romero has been able to use his Fall League time to continue working on his outfield play. At the start of his pro career, Romero was a bit of a jack of all trades, seeing time at a number of positions. But the Mariners asked him to focus on the outfield only in 2013 and he played mostly left field for Triple-A Tacoma.

"Just working every day in the outfield, instead of taking out three or four gloves, you're just taking out one glove and working on jumps and routes, working on your outfield routine alongside your hitting routine," Romero said. "It's a much easier progression."

Romero had a huge breakout in 2012, playing across two levels and putting up a ridiculous .352/.391/.599 line. Some of that was helped by the friendly confines of High Desert in the Class A Advanced California League, but he continued to rake in Double-A, as well. His line in 2013 -- .277/.333/.443 is much more modest by comparison, but Romero was held back by some injuries and was more focused on learning how to play the outfield to the best of his ability.

"It's going to be a progression," Romero said. "You want to be as consistent as possible. With the position change, I think in 2013, I was more focused on learning the outfield, the outfield defense. That took away a bit of my hitting. Now, it's more of a happy medium."

He certainly seemed to have his swing back on Saturday and Romero clearly enjoyed every minute. Being from Arizona didn't hurt, either.

"It's just an awesome atmosphere, especially with 6,000 people out here on a Saturday in a Fall League game," Romero said. "I'm from Tucson, so I had a bunch of friends and family members here, so that makes it that much more special."