The 36-year-old spent two years at Old Trafford having been signed by Sir Alex Ferguson back in 2004, playing 22 games in all competitions for the Red Devils.
The thoughts of everyone at Manchester United go out to Liam Miller and his loved ones at this difficult time. pic.twitter.com/CV2zT3xL6y— Manchester United (@ManUtd) November 13, 2017
Miller then joined League of Ireland outfit Cork City in 2015 before making the move to America to play for third-tier North Carolina-based side Wilmington Hammerheads in February 2016.
Sad to hear that my old team mate Liam Miller is battling cancer, my thoughts are with him and his family and I hope he can beat this and pull through.— Alex Bruce (@AlexBruce84) November 12, 2017
Such sad news about my old Room mate Liam Miller, Pray to God he pulls through this battle with Cancer, my thoughts and prayers are with him and his family.— Noel Hunt (@Noelhunt20) November 12, 2017
Very sad news about one of my old teammates Liam Miller, thinking of him and his family at this very difficult time.— Ian Harte (@ianharte23) November 12, 2017
All my thoughts and love with Liam Miller and his family— Darren O'Dea (@odea_darren) November 12, 2017
All thoughts and prayers go out to my old teammate Liam Miller tonight— Chris Sutton (@chris_sutton73) November 13, 2017
He’s not. He starts chemo tomorrow and is fighting hard really can’t go into any more detail than that out of respect for him and family. Praying he can get better. https://t.co/RLxfZ0wmAy— Tam McManus (@The_Tman10) November 12, 2017
Tweets sent by the ex-Republic of Ireland international's former clubs and team-mates suggest that he is battling a serious illness, with Tam McManus, Alex Bruce and Noel Hunt having mentioned cancer in their messages.
His former Hibs team-mate McManus also claimed that he is undergoing chemotherapy. He tweeted: "Awful news about Liam Miller keep the fingers crossed that he somehow pulls through. Was in the USA for treatment this month and [flies] back tomorrow to start chemo here. He’s still fighting it. Will say a prayer for him tonight."
Manchester United and Celtic offered their thoughts to the player and his family, while the likes of Ian Harte, Darren O'Dea and Chris Sutton also expressed their concern and passed on their support.