The deal approaches $20 million. The New York Knicks will have three days to match Toronto's offer.
Raptors GM Bryan Colangelo told reporters Wednesday the Knicks are considering re-signing Fields, a third-year guard.
"The Knicks have informed me they are very interested in retaining Landry," Colangelo said, according to the National Post.
Fields' agent, Chris Emens, said he had no knowledge of the Knicks' plans to match, but 'wouldn't be surprised' if they decided to go that route.
"However, I have no indication that they will do so," Emens said.
It's widely believed the Knicks won't match such a valuable offer, but their situation at shooting guard is unsettled.
The team re-signed J.R. Smith earlier Wednesday but still needs a replacement for injured guard Iman Shumpert, who will miss at least the first two months of the season while he recovers from surgery to repair a torn left ACL.
Fields, selected in the second round by the Knicks in the 2010 draft, was fantastic the first half of his rookie season.
But he seemed to struggle after New York acquired Carmelo Anthony in a blockbuster trade before the 2011 deadline.
Fields' scoring, rebounding and shooting percentage all decreased in his second year, when he averaged 8.8 points, 2.6 assists and 4.2 rebounds in a starting role.
Ian Begley is a regular contributor to ESPNNewYork.com.