Obviously, the news of the day Monday was the Indianapolis Colts announcing that coach Chuck Pagano has leukemia and that he will be hospitalized for at least a month. The good news is that Pagano's long-term prognosis is good. Doctors are optimistic that he will make a full recovery. He began treatment last Wednesday.

This situation, as owner and CEO Jim Irsay said Monday, is largely unprecedented. The team named offensive coordinator Bruce Arians as the interim coach, at Pagano's behest, and he led practice for the first time Monday.

"The one thing about this bunch of guys, you never have to ask them to work hard," Arians said. "They give you everything they’ve got. It was a very spirited practice, a very good practice."

Rookie quarterback Andrew Luck described his reaction, and what it was like to practice without Pagano.

“I think short of a death, probably the worst type of news you wanted to hear when you come in from a bye week," Luck said. "I don’t fully comprehend the severity of it or the situation. It will slowly hit us as the days go by, as you realize when you are out on the field and he’s not out there. It’s a little odd."

The Colts will face the Packers Sunday in Indianapolis.

Roster moves: Center A.Q. Shipley was promoted to the active roster, while linebacker Mario Addison was waived and cornerback DJ Johnson was released from the practice squad. Cornerback Marshay Green was signed to the practice squad. Green, originally signed as a free agent by the Arizona Cardinals, has one career tackle.

For more up-to-the-minute news and analysis from Colts blogger Evan Hilbert, follow @CBSColts.