Celebratory crotch grab costs NFL star $25k

Seattle running back Marshawn Lynch is reportedly facing a $US20,000 ($A25,000) fine from the NFL for his crotch-grabbing touchdown celebration in the Seahawks' 28-22 overtime win over Green Bay on Sunday.

The victory put the Seahawks into the Super Bowl, where they will defend their NFL crown against the New England Patriots.

Lynch wasn't penalised on the field for the off-colour gesture after his 24-yard touchdown run in the fourth quarter.

But the penalty imposed by the league follows a fine of $US11,500 ($A14,200) for a similar gesture after a touchdown against the Arizona Cardinals in November.

NFL.com and other media outlets, citing unnamed league officials, reported that Super Bowl week could get quite expensive for Lynch, the self-styled quiet man of the NFL.

Known for his reluctance to speak to the press, Lynch has already been fined $US50,000 ($A62,000) this season for failing to meet his media responsibilities.

Similar fines could escalate if he misses media sessions on Tuesday, Wednesday and Thursday in the build up to Super Bowl 49 in Phoenix, Arizona, on February 1.