Ronaldo, Messi at World Cup: Who else is playing their final tournament?

Cristiano Ronaldo, 41, is playing in his sixth World Cup, likely his last, after scoring 30 goals for Al-Nassr this season. Lionel Messi, 38, defends Argentina's title despite injury concerns. Scotland's 43-year-old goalkeeper Craig Gordon is the oldest player in the tournament. Several football stars are making their final World Cup appearances in North America.