DURHAM – Mike Elko’s voice kept going in and out during his press conference on Saturday night.

Given his Duke team played its second game in six days, that was understandable.

It was understandable that No. 21 Duke handled Lafayette in a 42-7 win at Wallace Wade Stadium, completing the mental hurdle of coming back from Monday night’s emotional win with a solid performance.

“We had to focus mentally more than physically,” running back Jordan Waters said after rushing for 112 yards and two touchdowns. “It was different but we managed it. It was more mental, knowing we had to take care of ourself and take care of business.”

Duke’s offense was balanced to the tune of 261 rushing yards and 254 passing yards. Its quarterbacks combined for the program’s single-record for completion percentage — Riley Leonard was 12-for-12 and Henry Belin IV was 8-for-8, and the lone incompletion was a spike.

And Duke created another couple of turnovers, running its total to five in the last three halves.

In most ways, this was what the doctor ordered. At times it was testy; enough to probably raise some voices on the sideline in the first half and in the locker room at halftime.

But it was also a game that Belin entered with four minutes left in the third quarter.

“We wanted to get him an opportunity to get out there with the ones when he could run the offense,” Elko said.

It wasn’t going to be enough for Belin to enter the game, make three handoffs, and call it experience. That’s why he escaped an unblocked rusher and threw on the run to Jordan Moore for a 49-yard catch-and-run on his first possession, and capped that drive with a 1-yard touchdown run — the first score of his career.

Belin added a 5-yard touchdown to Moore later on a slant, marking this the night for his first touchdown pass, too.

“He managed the offense really well,” Elko said. “Obviously he’s a kid that we have a ton of confidence in and at some point, he’s probably going to have to go out there and do that for us to win a game.”

Duke wanted to get a few more of its first- and second-year players into the game, but the Blue Devils were their own undoing in that goal. A 17-play drive swallowed up more than 11 minutes of the fourth quarter, so Duke scrambled and made some mid-drive substitutions.

The only other negative for Duke’s offense, which never punted, was a fumble by Waters. After Duke’s running backs lost one fumble last season — Waters at Pittsburgh — they’ve lost two in as many games, given Jaquez Moore lost one Monday night.

“I didn’t even need to have a conversation with him,” Elko said of Waters. “He actually came over to me and apologized and said, ‘Let me keep playing, please.’”

Duke’s week wasn’t easy; it just seemed that way because the Blue Devils were up 28-7 in each game and they put things on cruise control to end both games — that moment coming earlier against the FCS team than the ACC powerhouse.

Coaches love to say the most improvement for a team occurs from Game One to Game Two and the Blue Devils had two fewer days to turn that into reality.

“We learned that our drive has to be internal,” Elko said. “If we allow outside things to influence what we think about ourselves, how we prepare, what we think we have to do to get ready to be successful, those things will kill your season.”

Duke’s season is a week old. There are bound to be more moments, given the direction the arrow is pointed, in which the Blue Devils have to remain internally driven.

Saturday’s game was an encouraging sign they’ll be able to do that.