Yamamoto is scheduled to start Saturday's game against the Phillies.
With Caleb Smith (hip) on track to make a second minor-league rehab assignment this weekend, Yamamoto and fellow rotation newcomers Elieser Hernandez and Zac Gallen will all be extended at least one more turn. The performances of all three youngsters will likely have significant sway in determining which of the two will stick in the rotation once Smith is presumably reinstated from the 10-day injured list next week. At this point, Yamamoto may have the most job security of the trio after yielding only two runs to go with a 0.79 WHIP and 19 strikeouts in 19 innings through his first three outings in the big leagues.