The Tampa Bay Rays have been experimenting with their pitching staff all season, and now they are trying something manager Kevin Cash calls "unheard of."

On Saturday night, the Rays will give veteran reliever Sergio Romo the first start of his career. He is expected to pitch an inning or two to get the Los Angeles Angels off-balance, and then the Rays plan to bring in rookie Ryan Yarbrough.

"The way that their lineup stacks, generally speaking, is very heavy right-handed at the top," Cash told the Tampa Bay Times after Thursday's game. "It allows us, in theory, to let Sergio to come in there and play the matchup game in the first, which is somewhat unheard of -- up until Saturday, anyway."

The plan means that Angels heavy hitters such as Mike Trout and Albert Pujols will see Romo the first time around, giving Yarbrough an advantage their second and third times through the lineup.

"Then Yarbs can, in theory, have the availability to get deeper in the game," Cash said. "There's no more secret about the third time through the order. Everybody knows that. And that's kind of what this is about."

Romo, 35, has 588 career appearances. According to the Elias Sports Bureau, the only players in MLB history with more career appearances at the time of their first career start were Troy Percival (638), Todd Jones (632) and Chuck McElroy (603).

"Excited to see how he takes it, see if there's any nerves," Rays pitcher Blake Snell said.

The Rays (21-22) have been using a four-man rotation to start the season. In the fifth game, the start goes to the bullpen.

The Rays beat the Angels 8-3 on Friday night for their fifth straight win and their sixth win in seven games.