The Honduran international was dropped from the starting line-up for Wednesday night’s 4-1 win over Stjarnan in Iceland, with Charlie Mulgrew preferred at left-back for the Champions League qualifier.
Celtic have also been searching for a new left-back during the current transfer window and have been most recently linked with German defender Marcel Halstenberg of St Pauli as they seek to strengthen the position.
It has cast doubt on Izaguirre’s future at the club where his form has struggled to match the standards he set when being named Scotland’s Player of the Year in his debut campaign of 2010-11.
But Celtic manager Deila is adamant the 29-year-old, who is under contract to the Scottish champions until 2017, will remain a key member of his squad.
“Emilio will be back,” said Deila. “He’s a good player who has featured in about 95 per cent of the games since I have been here.
“We chose Charlie in Iceland and we’ll see what we do in the next game. Charlie is a good player with a lot of experience and he can fill different roles.
“Defensively, he talks and communicates better than Emilio has done recently, so it was better. We are also dangerous at set-plays and Charlie has great delivery.
“There are positive things in playing Charlie at left-back, but Emilio also has good things that he does going forward. He has speed. It’s the same as with strikers, you use them differently in certain situations.
“I don’t think Emilio has been anything different from last year. We talk a lot and he knows the things he has to work on to improve. He’s in our plans for the future.”
The deployment of Mulgrew at left-back comes at a time when the Scotland international finds his favoured holding midfield position in the possession of Nir Bitton alongside captain Scott Brown.
With Virgil van Dijk and Dedryck Boyata the first choice central defensive partnership, Mulgrew also faces a fresh battle to hold down a regular place in the starting line-up.
“Charlie understands how important he is to us,” added Deila.
“It is difficult for him to play centrally because of the players we have in those positions but he is also a very good player. Competition is hard for everyone but it is also important we can use Charlie at left-back.”
After completing a 6-1 aggregate victory over Stjarnan, the details of Celtic’s third qualifying round tie against Azerbaijani champions Qarabag have been confirmed.
Celtic are at home in the first leg, which will take place at Parkhead next Wednesday night with a 7:45pm kick-off.
The second leg will be seven days later on 5 August in the Tofig Bahramov Stadium in the Azerbaijani capital Baku, kicking off at 5:30pm UK time.