Andy Murray faces Polish player Jerzy Janowicz at the Wimbledon semi-final later.
It's a high pressure match for Murray who will be hoping that this year he can finally win the British Grand Slam.
Murray is ranked the second best player in the world at the moment and Janowicz is 24th but that doesn't necessarily mean it will be easy for Murray to win. Janowicz has a fast, powerful serve and is taller than Murray.
Andy's even been getting advice from Sir Alex Ferguson so what are his chances?
We asked you for your messages for Andy here are some of your comments.
"No pressure Murray, try your best and we will all love you for it. Keep calm and remember you can do it, whether you win or lose you will still be our number 1 Hero!"
Sarah, Luton, England
"Go Andy! I and all of America and Britain know you can do it! Do your best when you play."
Kiah, South Dakota, USA
"Keep calm and don't think about it too much. You are great."
Leyah, Northampton, England
"Go Murray, Go!! We believe you can do it!! You are amazing!"
Year 2 St Saviour's Primary School, London, England
"Come on Murray! You can do it! The whole country's behind you!"
Rose, Bristol, England
"Good luck Andy at Wimbledon. Dorcan Academy are right behind you."
Charlie, Swindon, England
"Good luck Andy! Go out there and be confident, tough and try your best! We are really hoping that you win and are looking forward to seeing you smash it! COME ON ANDY!!!"
Year 2, Lytham Hall Park Primary School, England
"I hope you win. It would be great and I would make some cakes for you!"
"Good luck Murray, you have supporters all over the world like in Australia!"
Katy, Brisbane, Australia
"Murray I am your biggest fan and my parents will be supporting you all the way too."
Saskia, Berkshire, England
"Well done for getting into the semis! Some upsets this year at Wimbledon but you stayed in it. Just keep calm do your best and play your heart out."
Cian, Dublin, Ireland
"Come on Murray! You can do it!"
Cia, Surrey, England
"Come on Murray I've seen all your matches so far and I know you can do it because you are the best!"
Molly, Rugby, England
"My whole family are rooting for you. I wish you the best of luck."
Holly, London, England
"Come on Murray this is your year this year go and win, you can beat Janowicz."
"Come on Andy. You inspire loads of children to play tennis and we trust you! YOU CAN DO IT!"
Megan, Northamptonshire, England
"Go on Andy everybody knows you will win. My advice is don't try and lob your opponent because he is massive!"
Arthur, London England
"Come on! You can do it. Don't give up."
Oliver, Edinburgh, Scotland
"Come on Andy you can do this. We all believe in you, so just keep up the good work!"
Joshua, Edgware, England
"Good luck Murray you can win it!"
Olivia, Stamford, Lincolnshire
"Murray you should just relax and play your best but don't let your nerves get to you."
Beth, Jersey, Channel Islands
"You have done really well to get this far and I think you could easily beat Jerzy Janowicz. Just to say you are my HERO."
Maximillian, Kent, England
"Just keep calm. Do not work yourself up otherwise you will never win."
Sebastien, London, England
"I wish you the best of luck and hope you win Wimbledon. Me and my friend Victor really like you."
Oliver, Bristol, England