Mane recently joined Merseyside outfit Liverpool from Premier League rivals Southampton in the summer transfer window.
According to BBC Sport, the Reds had to pay the Saints a transfer fee of £34 million to secure the services of the Senegal international winger. It has been reported that the transfer fee could rise to £36m.
England international full-back Flanagan, who is 23 years of age, believes that Mane will prove to be a success at Anfield.
“He has pace and power, and he’s a great finisher as well,” Flanagan told The Liverpool Echo about Mane. “I’ve seen it already in training this week. He’s a top class player and I think he’s going to be a great asset for us this season.”
Mane scored 11 goals and created 41 chances in 37 Premier League matches for Southampton during the 2015-16 season.
The former Red Bull Salzburg winger had a pass accuracy of 81% and a shot accuracy of 52%, and won 26 headers, 77 dribbles and 39 tackles.
During the 2014-15 campaign, Mane, who is 24 years of age, scored 10 goals and created 40 chances in 30 Premier League matches for the Saints.
Liverpool, who have already started pre-season training, will be looking to finish in the top four of the Premier League during the 2016-17 campaign.