It came on a day of late heartbreak for Africa as Uruguay and Iran each produced late goals in respective wins over Egypt and Morocco.

There was no doubt about the match of the day, however, as the battle between the two Group B heavyweights lived up to all its hype in a spellbinding encounter in the Fisht Olympic Stadium.

Spain went into the clash in a state of chaos just two days after Julen Lopetegui was sensationally sacked as manager following his surprise appointment as boss of Real Madrid.

The 2010 World Cup winners, now managed by Fernando Hierro, started slowly and were soon trailing the reigning European champions after Ronaldo won - and then converted - a soft penalty from his Real Madrid clubmate Nacho.

Portugal had chances to move further ahead but Spain equalised after Diego Costa showed typical strength in withstanding a series of challenges to power the ball home.

Ronaldo put Portugal back in front before the break after David de Gea could only parry his shot into the net, but Spain always looked dangerous and stepped-up the tempo after half-time.

Costa brought the scores level again with a tap in before a magnificent half volley by Nacho made amends for his earlier error and put Spain in front for the first time.

There was only one way Portugal were going to recover and that was through the outstanding Ronaldo.

After 88 minutes he pounced, curling a free-kick past the stranded De Gea to ensure the points were shared.

Ronaldo achieved his 51st career hat-trick and became just the fourth man to score in four different World Cup Finals after Brazil's Pelé, West Germany's Uwe Seeler and Germany's Miroslav Klose.

The game marked a huge improvement on the two earlier matches today.

Uruguay missed a series of chances against a Mo Salah-less Egypt in Group A at the Yekaterinburg Arena.

Injured Salah, who scored 44 times for his club Liverpool this season, remained an unused substitute as his team resorted to a defensive approach in their first World Cup Finals match since 1990.

Luis Suarez had missed four chances and Edinson Cavani hit the post from a freekick.

But a late strike by defender José Giménez in the 89th minute proved key to put Uruguay second to Russia on goal difference.

Iran left it even later to win their first World Cup Finals match since 1998 as Morocco substitute Aziz Bouhaddouz scored an own goal in the 95th minute.

Bouhaddouz inadvertedly headed into his own net with one of the last kicks of the game at the Krestovsky Stadium in Saint Petersburg.

Morocco had been the better side in the first half and nearly scored in the second when Iranian goalkeeper Alireza Beiranvand saved well from Hakim Ziyech.

Both will have to improve significantly, though, if they are to challenge Group B rivals Spain and Portugal.

Australia will play France at the Kazan Arena in Group C tomorrow before Peru clash with Denmark at the Mordavia Arena in Saransk.

In Group D, 2014 finalists Argentina will play Iceland at Moscow's Otkritie Arena before Croatia face Nigeria at the Kaliningrad Stadium.