Scouts for the Yankees, Giants and Blue Jays scouted Houston left-hander Wandy Rodriguez on Tuesday night against the Royals.
Rodriguez allowed two earned runs over seven runs in a lost to Kansas City.
The Astros will listen to offers for Rodriguez, according to sources.
Interested clubs are aware Rodriguez could have two years and $26 million left on his contract beyond this year, if he reaches the performance bonuses necessary to trigger the club option for 2014.
Yankees, Giants, Jays Scouting Wandy Rodriguez