Enner Valencia scored twice as Ecuador spoiled the party by beating hosts Qatar 2-0 in the first game of the World Cup.

Valencia had an early goal contentiously ruled out for offside at Al Bayt Stadium on Sunday, but Qatar were unable to heed the warning.

The clinical captain become Ecuador's leading World Cup goalscorer with a tally of four by opening the scoring with a penalty and struck again with a bullet first-half header.

Qatar looked out of their depth in their first ever World Cup match, failing to register a shot on target as Ecuador made an encouraging start in Group A.

Valencia looked to have put La Tri in front with a header in the third minute after goalkeeper Saad Al Sheeb flapped at a free-kick, but eyebrows were raised when Michael Estrada was deemed to be marginally offside following a VAR check.

The striker was not to be denied 13 minutes later, coolly sending Al Sheeb the wrong way from the spot after the shaky keeper brought him down.

Valencia capitalised on Qatar's defensive frailties again just after the half-hour mark, rising unmarked to meet Angelo Preciado's whipped cross from the right with a brilliant header that found the bottom-left corner.

Qatar had not posed a threat, but Almoez Ali somehow nodded wide from close range right on the stroke of half-time.

Valencia required treatment for a knee injury late in the first half but was able to continue and Ecuador continued to dominate after the break, Al Sheeb palming away Romario Ibarra's strike.

Qatar were devoid of ideas and Mohammed Muntari fired over when a rare chance came late on as Ecuador eased to victory, although there was concern when Valencia was withdrawn with 15 minutes to go seemingly still being troubled by that knee problem.