Former Wales forward John Hartson has received a message of support from seven-times Tour de France winner Lance Armstrong as he battles cancer. The 34-year-old Hartson, whose clubs included Arsenal, West Ham United and Celtic, was diagnosed with brain cancer last week and was in a critical but stable condition on Thursday after undergoing emergency surgery in Swansea. "My thoughts go out to John Hartson. Livestrong, John! We're pulling for you! Folks, hold him in your thoughts and prayers please," Armstrong said on his Twitter feed as he prepared for the 12th stage of this year's Tour. American Armstrong, 37, survived testicular cancer that spread to his brain and lungs in 1996 before embarking on his domination of the cycling classic. He came out of retirement in January to compete in this year's race. Last week fellow Tour de France rider Sebastien Joly thanked Armstrong for his support after recovering from testicular cancer in 2008. Hartson, who earned 51 caps for his country, retired in 2008. He was diagnosed with testicular cancer earlier this month before the disease spread to his brain and lungs.