Celtic trio Charlie Mulgrew, James Forrest and Adam Matthews have all signed contract extensions until 2016.
Mulgrew, 26, began his career with Celtic before joining Wolves in 2006 and then moving on to Aberdeen in 2008. He returned to Parkhead in 2010 on a three-year deal and the centre-back has been a key player for the club, winning a number of awards for his performances last season.
"It's good to get it signed and focus only on the football," Mulgrew told the club's official website. "Last year was a good one for me. I've been happy to be back. Things have been going well for me so hopefully that can continue.
"All the players here now understand what this club is all about, and for me, growing up as a Celtic fan, I understand fully what the fans expect here and hopefully we can deliver that.
"All the boys have a big drive and they've been here long enough to understand what the club is all about. It's a massive club and there is a big pressure here, week in and week out, but everybody's happy here.
"That's what you've got to do at a club like Celtic - the fans expect things, they expect you to win games, so I know the expectation levels here and hopefully we can continue doing well and winning games for Celtic.
"It humbles me to hear them singing my name and getting behind the team. Everyone appreciates it and it helps us. I know it's a cliche but they are the 12th man at times and it really helps the team."
The club later announced that Forrest has signed a deal until December 2016 and Matthews has committed until the summer of 2016.