MADRID, June 7 (Reuters) - Real Madrid and Spain midfielder Xabi Alonso has had successful surgery on a nagging groin injury, the Spanish La Liga runners up said on Friday. The 31-year-old was left out of the world champions' squad for the Confederations Cup later this month, after having struggled during the latter half of the season with his club. Alonso had the surgery with a specialist in Munich. Spanish media reported he would be out of action for three to four months. The club gave no estimate of how long he would be sidelined. (Reporting by Mark Elkington, editing by Mark Meadows) More...