Fraternity support: Cricketing world supports Australia batsman Phil Hughes

Australia batsman Hughes, who has 26 Test caps, was felled by a Sean Abbott delivery on day one of South Australia's Sheffield Shield clash with New South Wales at the SCG.

The left-hander, who stood dazed before falling after being hit, was rushed to hospital.

A St Vincent's Hospital spokesperson confirmed Hughes was in a "critical condition" after sustaining a head injury, and the results of his subsequent surgery are unlikely to be known for 24-48 hours.

Messages from around the cricketing world poured in via Twitter, with Australia head coach Darren Lehmann among those to pay tribute to the 25-year-old.

"Our thoughts and prayers are with Phil and his family! He is a great fighter and a great young man!" Lehmann wrote.

Australia opener David Warner, who was playing for New South Wales in Tuesday's game, left the field with Hughes, while national team captain Michael Clarke arrived at the hospital a short while later.

"Thoughts are with my little mate Hughsy and his family," Warner tweeted. "He is a fighter and a champion and he will get through this. Praying for you buddy."

Both former and current players tweeted similar sentiments, including Australia's all-time leading Test wicket taker Shane Warne and legendary seamer Glenn McGrath.

"Just heard the news about Phil Hughes, thoughts prayers are with you your family. Hang in there buddy, we are all fighting with u !!!" Warne wrote.

"Our thoughts are with Phillip Hughes his family. Wishing him a quick full recovery," tweeted McGrath.

Former South Africa wicket-keeper Mark Boucher added his support, tweeting: "Thoughts and prayers go out to Phil Hughes, his family,friends and teammates. He's a tough boy! Staying positive! #Hope #Faith."

Ex-India batsman VVS Laxman tweeted "Just got to know abt the injury to phil Hughes. Wishing him speedy recovery. Our thoughts and prayers are with him and his family #faith," with Sri Lanka batsman Mahela Jayawardene saying: "Just finish practices... Heard d news about Phil Hughes and shocked! Hope he recovers quickly. Good luck mate!"

Several more of Hughes' Australia team-mates, including Mitchell Johnson and Peter Siddle, also paid tribute and wished their friend a speedy recovery.

"Thinking of you mate! Hope everything is ok with u Hughesy," said Johnson, with Siddle adding: "Sad to hear about my little mate Hughsey. Thoughts go out to him and his family. Stay strong brother! X".