Gareth Southgate believes it will be an "interesting" World Cup if penalties akin to the one England conceded against Tunisia continue to be awarded.

England claimed a 2-1 win over Tunisia in their opening Group G encounter in Volgograd on Monday, but looked set to have to settle for a draw after Harry Kane's opener was cancelled out by a contentious spot-kick from Ferjani Sassi.

Sassi converted from 12 yards after Kyle Walker was penalised for catching Fakhreddine Ben Youssef with his arm.

England then saw two penalty appeals waved away despite Kane appearing to be impeded in the box on each occasion.

The Three Lions seemed to be running out of ideas as they struggled to create chances in the second half, having wasted a plethora of opportunities in the first.

However, Kane headed home the winner at the far post in the 91st minute to spare England's blushes, though Southgate still expressed his bemusement at referee Wilmar Roldan's decisions.

"We recovered from a really harsh decision and kept our composure," Southgate told a media conference. "Our set-plays were a threat all night, we worked on them and got just reward for that.

"I think if it's a penalty at one end it has to be a penalty at the other. Once the first one is given, it wasn't going to be overturned [by VAR] because it wasn't going to be a clear and obvious error.

"If penalties are going to be given for that, it's going to be an interesting tournament, I think there were similar offences at the other end of the pitch."

England midfielder Dele Alli appeared to be struggling with an injury in the first half but was not withdrawn until the 80th minute.

Southgate said of the Tottenham star: "We had to keep monitoring Dele. He was having a little bit of an issue before half-time but he felt he could carry on. The runs he was making and the way he was pressing the ball was still causing a problem."

Put to him that this was the perfect opening game for England as they emerged from it with a win but with plenty to work on, Southgate responded: "We are a team that is improving and developing, therefore there will always be things that we can be better at. We're a long way from perfection."

Southgate made his World Cup debut as a player against Tunisia in 1998, England starting that campaign with a 2-0 win.

Asked about the differences between that game and his World Cup bow as a manager against the same opposition, Southgate said: "I was sat in a drug testing room with Teddy Sheringham while everyone else was celebrating [in 1998].

"Tonight I'm at least able to experience a little bit of what the fans are feeling and the feel of the dressing room. But, of course, the difference being that, as a player you enjoy the moment a little bit longer, as a coach you're into looking at the game back on the way home and immediately focusing everybody around you on the next task. The enjoyment lasts a little bit less time."