Forster was outstanding for Celtic in their charge to the last 16 of the tournament last term and played a hugely significant part in their advancement out of the group stages.
This season he has been slow to reach the same level, but his saves in the game against Barcelona last night underlined his importance to Celtic.
The Englishman had little chance of preventing Cesc Fabregas opening the Catalan side's account after being left exposed by his defence, but two brilliant stops in the closing minutes to deny Neymar kept the score respectable.
Later Izaguirre praised the keeper's performance and said: "Fraser played well - he is a very good goalkeeper. Everyone here knows what he is capable of.
"I thought he had a very good game. But it is never about one player. We are a team and we win and lose games as a team. Our strength I think lies in playing for one another.
"We work hard and we try to stick to our game plan."
The Honduran full-back insists it is too early to write Celtic out of Group H despite losses to Barcelona and AC Milan leaving them with no points after their opening two games.
Next up is a double header against Ajax and although they are the only team now not to get off the mark in the group, Izaguirre was insistent there is too much football to be played to say it's all over for Celtic in the competition.
"We have lost two games but I do not think we have played badly in any of them," he said.
"We have been very unlucky in both of them. Although we have no points, there is time for us. Our next two games are very important.
"We know that we care capable of winning and we can get points.
"When you are playing in the Champions League, just one or two mistakes can cost you because you are playing against the very best.
"We believe that we can still show we are a strong team in this competition."
Izaguirre believes Scott Brown's dismissal was pivotal to the game. He said: "Scott is our captain and we stick together. He is a very good player and we missed him when he went off. I thought he was very unlucky.
"It is just football. Sometimes you get these decisions.
We felt it was unlucky but when you only have 10 men and you are covering so much ground when you do not have the ball it becomes very difficult.
"When you play at a team who have the players that Barcelona have, you need every player. It was hard for us with 10 men."
Izaguirre has told Celtic manager Neil Lennon that he will not welcome any time out of the side.
With Celtic coping on two fronts, with both European and domestic football, there is every chance that Lennon may tweak the team in order to give players a rest.
Celtic play Motherwell on Saturday but Izaguirre doesn't want any downtime.
"I want to play as many games as I can," he said. "No-one wants to find themselves out of the team for whatever reason. I don't think I need a rest. I want to keep playing."