POTSDAM, Germany, June 21 - Striker Andriy Shevchenko said Ukraine needed the midfield to drive them to victory over Tunisia on Friday, even though a draw is likely to be enough to seal a place in the last 16 of the World Cup.

"Any positive result will suit us, whereas the Tunisians need to win," Shevchenko told reporters on Wednesday. "But if we're not aggressive in midfield it will be hard for us.

"No way does it mean we'll be playing for a draw. I don't think any player who goes out ever plays for a draw because he knows how that can end up.

"We've got a very tough game ahead," said Shevchenko.

Since losing 4-0 to Spain in their first Group H game, Ukraine have recovered their confidence by defeating Saudi Arabia by the same margin.

They looked relaxed in training on a sunny evening at their base in Potsdam, on the outskirts of Berlin, and could even see the funny side of media reports that the Spanish debacle was caused by noisy frogs disturbing their sleep.

"It's not true, it's an invention of journalists," team spokesman Igor Miroshnichenko said. "There are frogs but they're not getting in the way of our preparations."

Central defender Vladislav Vashchyuk, expected to return after picking up a red card against Spain, said: "We're preparing according to plan and everyone's in good shape.

"We're laughing about those frogs now."