Miami Marlins superstar outfielder Giancarlo Stanton could be on the verge of possibly signing the biggest contract in the history of baseball according to Fox Sports's Ken Rosenthal.

The deal in question, could be upwards of 10 years and over $300 million according to Barry Jackson of the Miami Hearld. Stanton, 25 is coming off a career season that saw the power hitting outfielder hit .288/.395/.555 with 37 homeruns and 105 RBIs over 145 games. His 37 homeruns, .555 slugging percentage, 299 total bases and 24 intentional walks lead the National League in 2014. 

Getting ready to enter his 6th season in the majors, Stanton has already amassed 154 homeruns in his five seasons. For comparison reasons, baseball's all-time homerun leader Barry Bonds only amassed 117 homeruns in his first five seasons. 

According to Rosenthal, Marlins general manager Dan Jennings said "I wouldn't say we're close to anything." but also acknowledged that the two sides are in continuously talking. Which one source says is a "sign of progress". However, while Stanton is in talks about a possible $300 million deal, there are rumors circulating that the 25-year old may reject a $250 million offer from the Marlins as well. 

A 10-year deal would be ideal for the Marlins who would have Stanton's talents to their disposal until the superstar reaches his age 34 season. With Miguel Cabrera currently holding the world's biggest contract at 10 years, $292 million, Stanton will be looking to shatter this record. 

Stanton's recent chance of heart to possibly sign long-term in Miami may be with the teams' success in 2014 that saw the Marlins go 77-85 and finish 4th in the NL East, their best finish since Stanton's first season (2010) when the franchise finished 80-82.