Out-of-form Radamel Falcao, not Robin van Persie or Wayne Rooney, is Manchester United's most predatory striker, said Manchester City striker Sergio Aguero.
Falcao has only scored four goals in 23 games for United since joining on a season-long loan from Monaco but Aguero, another former Atletico Madrid striker, remains a fan of the Colombia international.
The 29-year-old scored 155 goals in 200 games for Porto, Atletico and Monaco before arriving at Old Trafford, and Manchester City top scorer Aguero believes that the quality is still there.
"They have a number of very talented strikers," Aguero told Sky Sports. "The one who in his career has been the most predatory is Falcao.
"He isn't having an easy time this season, but I really admire his commitment and his class and qualities are permanent. He is probably one of the most naturally gifted strikers in football at the moment."
Later, Falcao repaid the compliment and said he feels that they have to be particularly wary of Aguero, who has four goals in his last three derbies.
"They are a very talented team, with a danger all over the pitch, but Sergio Aguero has been a really dangerous player for Manchester United in the past matches," Falcao told reporters.
"He scored many goals, and always needs to be watched carefully. If there is one player more than others to watch out for, I'd say it is Aguero."
Aguero scored the only goal when City won November's Manchester derby at the Etihad Stadium but they go into the rematch behind United.
And while the Argentina international believes United have not always played to their potential this season, he feels they are an outstanding side when they play at their best.
"They are a team with a lot of great individual players, who can form an incredible unit when they work well together," he said. "But this season that has not always been the case.
"Some matches they don't seem to play at the maximum, with the attacking qualities that they have in the team. But then in other games, they have really shown that those qualities, so they are a bit unpredictable. We know we will have to be at our very best to beat them -- there's no doubt about that."
Aguero has equalled his longest goal drought as a City player by going six games without a goal, but has found the net six times in seven matches against United -- including one in the infamous 6-1 win at Old Trafford during City's 2011-12 title-winning season.
"I always love to score, but of course it is even more special to score in the big games," he added.
"If you score against United at Old Trafford it almost give you shivers, because you can feel the tense atmosphere with most of the stadium being really quiet, but the away end going crazy.
"At home at it is different, when the City supporters are really loud in these games, it sometimes gives me goose bumps when they sing my name."