Along with Osasuna right-back Cesar Azpilicueta, Manchester City are keen on left-back Natxo Monreal.
Accompanied by City scout Rob Newman, manager Mark Hughes was in Pamplona on Saturday to watch both defenders in action against Barcelona.
Hughes has both Spaniards under consideration as he is yet to be convinced by his current fullback options.
Monreal is also being tracked by Barcelona and Real Madrid.