Neil Lennon declared "Celtic comes first" after answering the call following Brendan Rodgers' sudden departure.
Lennon will take over immediately as Celtic travel to face Hearts on Wednesday, 24 hours after Rodgers left to take charge at Leicester.
The Celtic fans are in a state of shock over Rodgers leaving with a title still to be won but Lennon has told the players they cannot get distracted.
Lennon – who has been installed until the end of the season – told Celtic TV: "It's difficult circumstances obviously, there is a chasm to fill with Brendan leaving, who has done a remarkable job. But I'm here for the club.
"The club comes first, and obviously the players, and I want to bring as much success here in my time as I possibly can."
Lennon could not have asked for a much more difficult first few days back in the role he vacated in 2014.
After the trip to Tynecastle, where he was struck with a coin on his last visit as Hibernian head coach, he returns to Easter Road on Saturday for a William Hill Scottish Cup quarter-final against the club he left a month ago.
Lennon said: "Tough games but this is the business end of the season and looking at the mentality of the players, they look really focused.
"Whether this disrupts them a little bit, I have got to manage that for them, and make sure they stay fully focused.
"It's not about me coming back, it's not about Brendan leaving, it's about Celtic winning the league and hopefully winning another cup as well."
Lennon admits former team-mate John Kennedy, who has stepped up from first-team coach to assistant manager, will be vital for continuity.
"The players have been absolutely exceptional over the last two-and-a-half, three years and all I want to do is carry that on," he said.
"It's not broken, so I'm not coming in to revolutionise anything.
"I'm going to lean on John Kennedy a lot, he knows how it works, he knows the system, the routine and I'll be tapping into that a lot.
"I don't want this disrupting the flow. The players know what's at stake, eyes on the prize, and I'm just here to help them along with that."
