Suarez arrived at Anfield from Ajax in a €27.5 million deal and has propelled the Reds into a surprise Premier League title challenge this season, topping the scoring charts with 29 goals.
But Forlan, who now plays for J-League side Cerezo Osaka, has revealed things might have been very different had his international team-mate followed his advice.
"When Liverpool made him an offer," Forlan wrote in FourFourTwo, "I told him he should join Manchester United, but I also spoke well of Liverpool and their history.
"He loves playing at Liverpool. He likes the Premier League – and the fans love him because he's a striker's striker.
"He still chases everything, like Wayne Rooney used to before he moved deeper, and he's learned from his mistakes. We all make them."