The Italian striker has battled with injuries this season but after returning with a goal in the 6-0 rout of Newcastle United on Saturday, is looking to fill the void left by the suspended Luis Suarez.
"It had been a long injury for me and a long wait to score in the Premier League," he said.
"It's been hard. When I hurt my shoulder they said my season could be over but I fought back as I really needed to come back earlier.
"I took the minimum possible to get back training which was eight weeks instead of 12. Some people probably didn't think I could make it but I fought back.
"I can play a big part now not because Luis is suspended but because I am back fit.
"Whether Luis is available or not, we all need to focus on doing our jobs."