Osasuna are resigned to losing Riera after revealing they were in talks with an unnamed club about a deal for the forward.
It is now understood that Wigan are the mystery club chasing Riera, with talks at an advanced stage between all parties.
Riera, who came through the Barcelona youth ranks, impressed for Osasuna last season finishing as the club's top scorer with 13 goals, including two goals in a 2-2 draw with Real Madrid.
A number of clubs are thought to have expressed an interest in Riera, but Wigan are hopeful of luring the 27-year-old to the DW Stadium.
Wigan boss Uwe Rosler is keen to bolster his attacking options next season and sees Riera as a key addition to his plans as he aims to build a side capable of winning promotion back to the Premier League.