England goalkeeper Jordan Pickford has told ESPN FC that his side cannot underestimate Tunisia in their World Cup opener as he has first-hand experience of the dangers presented by former Sunderland teammate Wahbi Khazri.
Khazri, who spent last season on loan at Rennes from Sunderland, is one of only a handful of Tunisia players to have played in Europe's top leagues, with the majority of coach Nabil Maaloul's squad based in their domestic league.
The attacking midfielder spent the 2016-17 season at Sunderland with Pickford, who left for Everton a year ago, and he said Khazri's ability at set pieces will be a major threat in the game in Volgograd, Russia, on Monday.
"I played with Wahbi at Sunderland, so if I get the nod, I've got to be ready for his corners because he doesn't mind whipping them under the crossbar," Pickford told ESPN FC. "He is very good at set-pieces and finishing from outside the box, so I have to be ready.
"I watched the Portugal-Tunisia friendly before we came to Russia and Tunisia are a good side. They will be underrated, so we have to be ready, and the same for Panama. In both games, we'll be expected to have a lot of the ball and when we create chances, we have to take them and be ready to defend against them as well.
"But that's the good thing about the internet. There's a lot of stuff on there to go and get your research done."
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Pickford goes into his first World Cup having been handed the No. 1 shirt by manager Gareth Southgate despite being capped just three times for his country.
Stoke City keeper Jack Butland has eight caps, with Burnley's Nick Pope having only made his international debut as a second-half substitute against Costa Rica in Leeds, England, last week.
But with Southgate overlooking Joe Hart when selecting his three goalkeepers, Pickford, 24, insists that a lack of experience will not be an issue for England's keepers in Russia.
"It doesn't affect me and I don't feel it matters that I only have three caps," Pickford said. "I'm hoping to get more caps and the only way you can get experience is by playing, so I don't think you can say there are only so many caps between us because experience comes by playing and I'll be ready.
"We haven't been told who the official No. 1 is yet, but getting the shirt is massive for me and a massive honour, to have that No. 1 shirt. Some great goalkeepers have worn that No. 1 shirt in World Cups for England, so I have to think really positively about taking it forward."