Spain and Portugal clash on Friday in an early highlight of the World Cup in Russia as the Spanish camp insist they are united despite this week's extraordinary sacking of coach Julen Lopetegui.

Egyptian fans, meanwhile, will hold their breath to see if prolific Liverpool striker Mohamed Salah really has recovered from the shoulder injury he suffered in the Champions League final as the Pharaohs take on Uruguay.

But after host nation Russia's rousing 5-0 win over Saudi Arabia in the tournament opener, the highlight of the day will be Spain's clash with Cristiano Ronaldo's European champions in Sochi.

The Spanish team had been tipped as one of the favourites to win the trophy for a second time after a two-year unbeaten run under Lopetegui.

But Wednesday's snap decision by the Spanish Football Federation to dump Lopetegui, after he announced he would take over at Real Madrid post-tournament, has left the team reeling.

Former Real Madrid stalwart Fernando Hierro has been thrown into the deep end as head coach, with little coaching experience and huge pressure on his shoulders.

Captain Sergio Ramos and Hierro put on a united front on Thursday as they contemplated the opening Group B meeting against their neighbours and arch-rivals following two days of chaotic upheaval.

"There is nobody better than Fernando. He was a great player and has known us for a long time," said Ramos.

Real's appointment of Lopetegui could, the federation apparently feared, have opened up Spanish football's age-old faultline between the squad's Madrid and Barcelona-based players.

Ramos, who also skippers Real Madrid, insisted this week's events had not upset any relationships.

"There are no cracks. We are all individuals and we all think differently, but the collective idea is the same -- we are here to go for the World Cup," he said.

Almost 5,000 kilometres away, Lopetegui was being unveiled as the new Madrid coach.

The 51-year-old described the day he was sacked as "the saddest day of my life since the death of my mother".

Ronaldo and Portugal have enjoyed a calmer build-up but the 33-year-old reigning World Player of the Year knows that Russia is probably on his last chance to win a World Cup.

The Real Madrid superstar could play on for years yet, but it is difficult to imagine him leading Portugal to glory in Qatar in 2022.

A 19-year-old Ronaldo was playing the last time Portugal beat their Iberian rivals in a major tournament, winning 1-0 to eliminate Spain in the group stage at Euro 2004.

He has gone on to become his country's leading scorer with 81 international goals in 150 appearances.

Yet one doubt hangs over him: his form in a Portugal shirt has never matched his heroics for Manchester United and Real, and his World Cup scoring record so far is poor with just three goals in three tournaments.

Egypt coach Hector Cuper says Salah is "almost 100 percent certain" to start against Uruguay in the Group A match in Ekaterinburg, nearly three weeks since he left the field in Kiev clutching his shoulder in agony after being wrestled to the ground by Ramos.

Friday's other Group B fixture pits Iran, coached by former Real Madrid manager Carlos Queiroz, against Morocco, guided by Frenchman Herve Renard.

Queiroz freely admits Iran are the underdogs of the group but has used a decision by Nike to halt supplies of boots to some of his players because of sanctions as a way to unite his squad.

"It has been a source of inspiration for us," Queiroz told Sky Sports.

He said Nike "should come out and apologise because this arrogant conduct against 23 boys is absolutely ridiculous and unnecessary".