Shohei Ohtani will be on the mound for the Los Angeles Angels on Friday night against the Seattle Mariners in Anaheim, Calif., coming off his worst start of the season.

Ohtani, a right-hander, gave up five runs and nine hits in six innings against the Houston Astros last Friday, his ERA rising from 2.91 to a season-high 3.30. The nine hits allowed were the most in a game against him all season, and the five runs he surrendered matched a season-worst.

The Angels, who have won four games in a row, use a six-man starting rotation, giving all of the starters an extra day between starts, but it's geared more toward Ohtani than anyone else considering he's an everyday player as well.

Ohtani (5-2, 3.30 ERA) has had five days of rest between starts on the mound all season, except for one start when he had three days off following a two-inning, 31-pitch outing. Friday, though, Ohtani will pitch on six days' rest for the first time, with Angels manager Phil Nevin using Monday's off-day to push everyone back a day.

"His stuff is still pretty crisp," Nevin said. "Moreso as I start going through this, we're looking at [the potential of] over 200 innings for the first time in his career. He's approaching places he hasn't been before. So I just felt like it was good to give him an extra day now."

In his first six starts of the season, Ohtani went 4-0 with a 1.85 ERA; in his past six starts, he's 1-2 with a 4.62 ERA.

Ohtani has hit for a high average when he starts on the mound, batting .362 (17-for-47). However, he hasn't hit for power, getting just one of his 16 home runs in games he pitches.

Ohtani has pitched well against Seattle in his career, going 5-0 with a 1.64 ERA in seven starts.

Right-hander Luis Castillo (4-3, 2.55) will make his 13th start of the season for the Mariners. He shut out the Angels on two hits for 5 2/3 innings in his only start against them this year on April 4. Overall, he is 2-0 with a 1.93 ERA in three career starts against the Angels.

Since giving up a season-worst seven runs (five earned) in a loss to the Boston Red Sox on May 16, Castillo has turned things around. In three starts since, he has allowed just one run in 19 innings, striking out 24.

"I feel phenomenal," Castillo said through an interpreter. "Thank God that I've had the help that I've had. I'm just going to continue to do what I do best, and that's hopefully what we continue to see."

Using his secondary pitches at the right time, particularly his slider, has made a difference, Castillo said.

"They have been working really well for me," he said. "That's what secondary pitches are for, to keep batters guessing and confused about what's coming next.

"The only (other) difference is we've been putting more time in with the pitching coach (Pete Woodworth) and my confidence has grown, which is why I'm having the results I do."