OWINGS MILLS, Md. -- Will Robert Griffin III or Lamar Jackson serve as the Baltimore Ravens' primary backup to Joe Flacco?

"I’m not saying," Ravens coach John Harbaugh said Monday.

The Ravens open the regular season on Sunday, playing host to the Buffalo Bills. While the Bills named Nathan Peterman as their starting quarterback on Monday, Harbaugh was tight-lipped about his quarterback situation.

The intrigue surrounds Baltimore carrying three quarterbacks for the first time since 2009. The Ravens decided to hold on to Griffin, which gives them two Heisman Trophy winners in Griffin and Jackson.

It would be unusual if the Ravens put Flacco, Griffin and Jackson all active on the 46-man roster Sunday. According to ESPN Stats & Information, only one team had three active quarterbacks in Week 1 last season, when the Bills went with Peterman, Tyrod Taylor and Joe Webb (who also played wide receiver and special teams).

"It wouldn’t be any more than three. It won’t be any less than two. We’ll see," Harbaugh said on the number of active quarterbacks he'll have for Sunday. "I really don’t know. Hey, it’s day-to-day."

Griffin was the more consistent quarterback throughout training camp and the preseason. Out of the NFL last season, Griffin completed 66 percent of this throws and produced an 87.7 passer rating in the preseason.

Jackson, the No. 32 overall draft pick this year, was erratic in his first three preseason games before improving in the last two.

In June, Harbaugh indicated Jackson would be active on game days. That also was when the Ravens were putting their rookie first-round pick and Flacco on the field at the same time.

On Monday, Harbaugh was noncommittal when asked if Jackson would be suiting up for the opener.

"We’ll do whatever is best for our team," Harbaugh said. "Any given Sunday, we’ll have the 46 guys up that gives us the best chance to be successful."