The Post Sports Live crew goes on the record by predicting whether the Denver Broncos or the Seattle Seahawks will win Super Bowl XLVIII. (Post Sports Live/The Washington Post)

The text messages came first, their subject and frequency enough to stir Jack Del Rio’s concern.

Is Coach okay?

It was the Saturday of the Denver Broncos’ bye week, a time meant for recharging and, in a stressful job, a few days of worry-free living. Now this. Del Rio, the Broncos’ defensive coordinator, called his boss, Coach John Fox, who at first played down a heart ailment that had become increasingly serious. He would undergo tests, Fox said, but nothing more.

A day later, it was Fox who called. “John Elway is going to be calling,” Del Rio recalled Fox telling him. “He’s going to want you to take over.”

Fox, the 58-year-old coach in his third season with the Broncos, learned during that weekend in early November that he needed emergency open-heart surgery to replace his aortic valve. Fox had planned to address the issue after the season, but his doctor told him the procedure couldn’t wait. A normal valve is the width of a quarter; Fox said this week that his valve had collapsed and was the size of a pinhead.

The Post Sports Live crew discusses what a second Super Bowl win would mean for Peyton Manning's legacy. (Post Sports Live/The Washington Post)

And so Del Rio, the ex-NFL linebacker and former Jacksonville Jaguars head coach , was named interim head coach, left to keep Denver’s season on track — preserving the Super Bowl hopes of one of the league’s most talented teams.

When the Broncos reconvened the following Monday, the day after Fox had surgery in Charlotte, where he had coached the Carolina Panthers for nine seasons , Del Rio gathered the team in a meeting room. Some players had read about Fox’s upcoming procedure on the Internet; others saw the news on TV. Del Rio addressed it anyway, reiterating Fox’s policy of, as Del Rio put it Wednesday, keeping everyone on the same page.

“We had a blueprint,” he said. “We had a routine, and we wanted to make it as seamless as possible for all involved. We talked about the need to pull together; the fact that it needed to be a collective effort, really, from everybody in the building.”

And this became a hallmark of the next four weeks: Del Rio sticking to the schedule, from practices to the day-to-day business of running a team. He kept Fox’s chair unoccupied during coaching meetings, and equipment staffers were instructed to leave Fox’s locker as he had left it.

“We were already set in our ways, and I think Coach Del Rio did a great job in not straying away from that,” cornerback Quentin Jammer said Wednesday. “We already had a regimen that worked, and he stuck to it.”

Del Rio began each morning’s meeting with an update on Fox’s condition and recovery, and a camera was set up in the team room for a conversation via Skype with the head coach. After each update, the talk quickly returned to football. The Broncos would spend four weeks without Fox, who nonetheless talked with his staff and watched game footage on his iPad in Charlotte, and the team played three AFC West games and faced the New England Patriots.

Del Rio coordinated the defense and oversaw the entire team during this time, and his poise — and that Denver went 3-1, losing only an overtime thriller to the Patriots — pushed Del Rio’s name back onto the head-coaching radar. He reportedly interviewed for the position at the University of Southern California and was considered for a handful of the NFL’s seven openings.

“There certainly are opportunities each and every year,” he said, “and at some point it will match up with what somebody’s looking for and what I offer. In the meantime, I’m going to enjoy the heck out of my opportunity here.”

On the first Monday of December, the day after the Broncos defeated division rival Kansas City to take a commanding lead in the AFC West, a few players heard a familiar voice coming from a hallway.

“You’re like: ‘Well, there he is,’ ” running back Knowshon Moreno said.

Doctors had cleared Fox to return to the team facility, and as Del Rio had done four weeks earlier, Fox began his first team meeting by addressing his health. He was fine, he told players, and then the discussion turned to that week’s opponent, the Tennessee Titans. Later, he occupied the vacant chair in the coaching offices.

“He didn’t lose a beat. He was the same guy,” Moreno said. “Nothing really changed. That was awesome to see.”

Occasionally, players would ask Fox about his health, and considering the built-in concern of a major heart surgery, their early instincts were to tread lightly around the recovering coach. Instead, Fox shook it off. “I’m fine. I’m ready to go,” Moreno recalled Fox saying, and back to football they went.

Added cornerback Dominique Rodgers-Cromartie: “He told us he was feeling good and left it at that.”

The coach has reiterated often this week that he’s healthy.

“The first thing I say is I’m 150 percent better,” Fox said this week. “I feel way healthier than I did nine, 10 weeks ago.”

Players took his word for it, and Del Rio resumed his full-time position as defensive coordinator. Fox was back to coaching as he always had, and now nearly two months since he left the team, the Broncos have used the experience as an obstacle they’ve overcome. If they survived losing their head coach for a month, how difficult can it be to win a game?

“A scary, scary thing,” Jammer said of the ordeal, “and we overcame it as a team. He came back with us, and we’re in the Super Bowl now.”