But he predicted he will have a fight on his hands winning back his first-team place from Sebastien Faure when he regains full fitness.
Foster has been sidlined with ankle ligament damage since limping off in the 3-1 win over SPFL League One rivals Dunfermline at Ibrox last month.
The right-back is making good progress in his rehabilitation and is optimistic he will be able to do some light running within days.
And, all being well, the 28-year-old will be available for selection by manager Ally McCoist before Christmas.
"Things are progressing as we expected," he told SportTimes. "We are building it up on a weekly basis.
"With it being a ligament injury, I have lost a lot of strength and I need to take my time increasing that.
"But barring any setbacks, I am hopeful I will be back doing a bit of light running next week. Then we just have to wait and see how things progress.
"But players who get this type of injury normally spend between six to eight weeks out. Barring any complications, I am hopeful I will be back playing in six weeks."
The former Aberdeen man, though, knows he will not walk straight back into the Rangers side when he finally recovers from his injury.
For he has been greatly impressed with how French defender Faure has fared since taking over from him at right back.
The 22-year-old has helped the Light Blues rearguard keep a clean sheet in three of four games he has started in the last month.
"Before I got injured Seb was doing really well in training and in the matches that he was involved in," said Foster.
"He had played for the team at centre-half and now he has moved across to right-back. He has done extremely well along with the rest of the team.
"He is still relatively young. But defensively he is very good. And he is an aggressive player. He also likes to break forward whenever he can.
"I am obviously wanting to get back fit and playing in the team again. But I realise that I have got a fight on my hands when I get myself fit again with Seb doing so well."
Foster added: "The manager always stresses that it is not just the players on the park who are important. It is the whole squad who are going to bring success during a season
"It is up to the players who have not been featuring to take their chance when they get into the team. Everyone who has come in since we have picked up injuries has done a really good job."
Faure helped Rangers keep a clean sheet in their Scottish Cup fourth-round win over SPFL Championship opponents Falkirk away from home on Saturday.
Foster was delighted to see the Glasgow club, who will now face either Ayr United or Dunfermline in February, progress in the competition.
He is hopeful that he can be involved in the latter stages of the tournament - and possibly even help the Gers challenge for the silverware.
He believes the win over a full-time club from the division above them shows they can compete with clubs from the top flight despite their third tier status.
"The game against Falkirk was massive for us," said Foster. "I think the win has been played down a little bit by some people.
"But the game against Falkirk was probably our biggest game of the season so far. To keep a clean sheet and score two goals was just fantastic.
"Falkirk are a good side, especially at home. They have been scoring goals and doing well in the Championship. To win there will give us a lot of self-belief as a team.
"The Scottish Cup is a great competition for the players and the fans and it is one that hopefully I can be involved in later on this season."
Foster attends every Rangers home game and was pleased to see his team-mates beat Forfar 6-1 on Tuesday night and set a new post-war record for consecutive wins.
The former Bristol City man revealed that winning 19 games in succession in all competitions has brought the squad closer together.
"I don't think players are concerned with records before games they are playing in," he said. "But it is a nice accolade for them once they have achieved it.
"Yes it's the third tier, but you can only win games in the competition that you are in. There is a real positive buzz in the dressing room at the moment."
Foster suffered his ankle injury after a late challenge by Dunfermline player Callum Morris that upset Rangers manager McCoist at the time.
But the full-back, who is one of five first team players out of action injured at the moment, said: "People are going to make tackles and you are going to suffer injuries as a result.
"From what I can remember, he went for the ball. I just got their a bit before him. I don't think there was any malice."