"I will work much harder to repay the belief shown in me. I signed this new contract to stay here for a few more years because it's a great honour for me," Coutinho said.
"It gives me great happiness because I was welcomed here with open arms by everyone at the club and the supporters right from my first day."
Coutinho has scored 34 goals in 163 appearances since he joined the Merseyside club from Inter Milan in January 2013 and has played a pivotal role in Liverpool's solid first half of the season.
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Liverpool are fourth in the Premier League standings after 22 games, 10 points behind leaders Chelsea, who they face at Anfield next Tuesday.
(This version of the article corrects the number of games played to 22 from 21 in final paragraph)
(Reporting by Shravanth Vijayakumar in Bengaluru; Editing by Alison Williams)
