Sources in the Minnesota boxing community say ex-world champ Will Grigsby is preparing to challenge for a third world title, likely on the Winky Wright-Felix Trinidad undercard in May.  Grigsby is training to face IBF 108-pound champion Victor Burgos, who became Boxingtalk's #1 junior flyweight when Rosendo Alvarez moved up to flyweight.   Grigsby, the first Minnesotan to win a world title in a major boxing organization, hopes to regain the belt he lost to the legendary Ricardo Lopez in 1999. Grigsby last fought at light flyweight in 2000 when he beat Nelson Dieppa for the WBO title but was later stripped and the decision changed to a NC due to a positive test for marijuana. He has fought twice at super flyweight since being released from prison last year after serving 27 months for assault. The fight cannot be considered official because Grigsby is not yet ranked by the IBF, but that sanctioning body has been known to manipulate its ratings in these situations (see Derrick Jefferson and Andrew Golota in 2004). Remember where you heard it first!