Switzerland boss Vladimir Petkovic has refused to ignite a political row ahead of their key World Cup clash with Serbia.

The teams face off in Group E on Friday with Serbia top after their opening win over Costa Rica.

Stoke midfielder Xherdan Shaqiri is expected to continue to wear footwear which will have the Kosovo flag on his right heel to pay tribute to his heritage.

Stoke City v Crystal Palace – Premier League – bet365 Stadium
Stoke’s Xherdan Shaqiri plays with two flags on his boots (Dave Howarth/Empics)

Shaqiri’s flag – he also wears a Swiss one on his left boot – has been perceived as provocation with Kosovo declaring independence from Serbia 10 years ago – which Serbia has refused to recognise.

But when asked about the flags Petkovic insisted he will focus on Switzerland’s performance.

“Well, I will speak with the players and I will tell them we’ve had a great match against Brazil,” he told a press conference.

“That’s not enough – we have to play better against Serbia. We have to give our best and we want to win the match.

“We want to be strong against every opponent and we want to be able to show tomorrow that we are at a very good level and that we can beat any side.”

Valon Behrami is a doubt after coming off in their opening 1-1 draw with Brazil while Petkovic is expecting more from Shaqiri.

He said: “I expect from him and from everyone else in the team and myself, I always expect more and better. He is very, very positive. He is never satisfied with what he has already achieved – he always wants to go further.”

Serbia have never reached the knockout rounds of a World Cup but they will if they can beat Switzerland at the Kaliningrad Stadium.

Head coach Mladen Krstajic was also reluctant to talk politics and wanted to focus on the game.

”I’m not into politics,” he said. ”We have our goals. We’re here for sports to represent our country in the best possible way and we’re not at all interested in anything else.”

Serbia beat Costa Rica 1-0 in their opening match and Nemanja Matic admits the squad are ready for a “hellish” game.

“We’re aware of what’s in store for us,” he told a press conference. “They have quality throughout. Great individual players.

“We expect a hellish game but we’re ready for anything.

“Of course we’re aware that if we win we would progress. We will do our best but we are facing a very good team in Switzerland. They will also try to be a threat, to win three points.

“They have a lot of quality. We respect them. We will give our best until the end. We have the quality to be a threat against them.

“With respect to a draw, I never start a match hoping for a draw. We always want to win. It’s not always possible.

“They are a very good team. They occupy the sixth place in the rankings. They’re the favourites. We respect them but are aware of our own qualities.”