It’s been billed as the battle of the green and whites.

Except neither Celtic nor Real Betis will be in their traditional colours tomorrow night.

Ange Postecoglou takes his team to the Benito Villamarin stadium for their Europa League Group A opener.

But both sides will be in their change kits due to UEFA regulations, according to Estadio Deportivo.

The Betis kit has been ruled "incompatible", with the governing body imposing restrictions on things like sponsor sizes, which brands can be displayed and, of course, kits being too similar.

It means the hosts will play in the gold away kit, while Celtic will sport their mainly white third kit,

Article 55 of the Europa League regs state: “For all competition matches, the home club has the first choice as to which of its official playing attires announced on the playing attire approval form it wears for its home matches. In the qualifying phase and play-offs the clubs agree on the colours to be worn from the playing attires announced on their playing attire approval form.

“If the clubs are unable to agree on the colours to be worn by their teams, they inform the UEFA administration, who takes a final decision. As of the group stage, the UEFA administration proposes which colours should be worn. The proposals can be changed at the request of the clubs provided that the alternative solution does not lead to clashes in any part of the attires. If no agreement can be found, the UEFA administration takes a final decision.

“In any case, if the referee notices on the spot that the colours of the two teams could lead to confusion, he decides on the colours, after consulting the UEFA match delegate and the UEFA administration. As a rule, in such cases it is the home team that has to change colours, for practical reasons.”

It is because of Celtic that Betis play in green and white in the first place.

The founder of Sevilla Balompie, Manuel Ramos Asensio, was sent to Dumfries to learn English as a boy, and ended up making regular trips to Celtic park with his friends.

On his return to Spain, Asnesio founded Balompie and after becoming captain, changed their colours from blue and white to green and white, except he inverted Celtic’s traditional hoops so that Balompie played in green and white stripes after the club sent him the required materials.

The club then merged with Real Betis FC to become Real Betis Balompie, as they are known today.

Group G is very much the group of green and white, with Hungarian champions Ferencvaros also playing in those colours.