CINCINNATI -- What Terry Collins hinted at on Tuesday became official on Wednesday: the Mets are going to begin using a six-man pitching rotation this week.

The one exception is that right-hander R.A. Dickey will remain on his normal five-day routine. Rookie right-hander Jeremy Hefner will be added to mix on Sunday at Washington. Chris Young will be the first starter to have his normal day pushed back to maintain Dickey’s five-day status. Young was originally scheduled to start Sunday but will now go on Tuesday against Colorado at Citi Field.

Collins and pitching coach Dan Warthen have worked out a schedule that could carry the team the rest of the season.

“Certainly the health of our staff to make sure they remain healthy the rest of the season,” Collins about the motivation. “We think this is going to really give us the best chance to compete at the level we want to compete because we’re going to be playing some teams that are playing for some things very special. We want to make sure we are running the best guys out there."

Tuesday night’s opener against the Reds at Great American Ball Park was the first in a string of 23 games in 24 days for the Mets. Young held the Reds scoreless over the first 5-2/3 innings before giving way to the bullpen.

Dickey is starting tonight’s second game against the Reds and will make his next scheduled start next Monday at home against Colorado.

Hefner (2-4, 4.77 ERA) has appeared in 17 games, including six starts, this season. His last start came on Aug. 4 at San Diego when he pitched six innings and allowed just one run on five hits in a 6-2 win against the Padres.

“This can only benefit myself by showing my versatility,” Hefner said. “This is something I’ve done before and I’ve started after bullpen outings and had success. I’ve learned from this whole year, experienced some downs and ups so I’ll just continue to work hard and win a ballgame.”