Real Madrid manager Juande Ramos, who was manager of Tottenham Hotspur when Robbie Keane was sold to Liverpool, has told Rafa Benitez that he made a big mistake in letting the striker leave Anfield.
Speaking ahead of next week's Champions League last-16 clash with the Reds, Ramos said: "You can't tell me Robbie will not score goals at a top club."
"He's definitely a match winner for any club and if he were still at Liverpool, I would be telling my defenders to watch for him."
Liverpool forked out £20million for Keane last summer and Ramos could not disguise his surprise at Liverpool's decision to sell him back to his old club for £12m just six months later.
"It was a lot of money to lose on Robbie over such a short space of time - especially in this market," Ramos said. "Let's put it this way. I wouldn't want to lose that amount of money on one player."
"Maybe Liverpool should have kept Robbie until at least the summer to give him more time and try and get the right price for him when there was more time to do so!"
Since Ramos replaced Bernd Schuster at Madrid in December he has dragged Los Blancos from fifth place in La Liga into second place, 10 points behind leaders Barcelona, and was quick to remind Liverpool of the pedigree of his new club ahead of their Champions League clash.
"[Liverpool] are a massive European Cup club but the fact is we are bigger - bigger than anybody in this competition," said Ramos.
"Everybody knows about Liverpool's successes but at the same time everybody knows we are the most famous and successful club in Europe.
"For the Real Madrid fans it has been too long since they won the European Cup and with Barcelona so far ahead in La Liga before I arrived maybe this is our best chance of a major trophy this season."