BILBAO, Spain -- The San Antonio Spurs have expressed interest in signing Mexico star center Gustavo Ayon, ESPN.com has learned.

Ayon ranks as one of the top free agents playing at the FIBA World Cup starting Saturday in Spain and, according to league sources, has emerged as a late-summer target for the NBA's reigning champions.

The Spurs also have their eye on Ray Allen, should the guard decide to return for his 19th season. Allen has drawn interest from a number of teams, including the Clippers, Cavaliers and Mavericks.

As far as Ayon, sources say San Antonio remains determined to re-sign Australian center Aron Baynes -- who will square off against Ayon on Wednesday when the Aussies meet Mexico in Group D play -- but has identified Ayon as both a potential Baynes replacement or a possible addition to the roster even if a new deal with Baynes is worked out.

After leading Mexico on a fairy-tale run last summer to the FIBA Americas championship and a spot in FIBA's quadrennial championship for the first time in 40 years, Ayon suffered a serious shoulder injury in training camp with Atlanta in October that ultimately limited him to just 26 games with the Hawks last season.

Ayon has said numerous times this month that his preference is to stay in the NBA but that he is likely to decide on his future only after playing in this World Cup for Mexico, which landed in Group D and can advance to the single-elimination portion of the tournament if it finishes higher in pool play than Angola and South Korea.