Okazaki has scored five goals this season for Mainz who fifth in the Bundesliga league.
The Japan International is contracted at the club until the summer of 2016 but the German side could be tempted to cash in for the 28 year-old in the next window if the right offer is made. Mainz could accept offers for around 8- 10 million euros.
In the last year, the number 23 has scored 39 goals in 79 games – averaging a goal every other game.