The first round of games in the group phase of this season’s Europe League get under way on Thursday as 23 clubs make their first appearance at this stage of the competition – including Tromso - with some having particularly tough opening fixtures.
The Norwegian side qualified after Besiktas were thrown out for match-fixing and travel to England to meet Andre Villas-Boas' side for the first time.
Michael Laudrup's men made short work of Petrolul Ploiesti in the qualifying play-off, but know they will have to raise their game at the Mestalla.
That will give hope to Swansea, who have added Jonjo Shelvey and Wilfried Bony to their ranks during the close-season to support last season's top scorer Michu.
The surprise package in the Portuguese Primeira Liga last season – Pacos de Ferreira – travel to Florence to face Vincenzo Montella's confident Fiorentina.
Sevilla - who won this competition in 2006 and 2007 – face Estoril in their opening Group H match.
Unai Emery's side came close to earning a 2-2 draw at Barcelona on Saturday before conceding a 94th-minute goal, but their Camp Nou performance will give them plenty of competition heading into Thursday's game.
The likes of Willian, Samuel Eto'o and Lassana Diarra have all left the club as Anzhi look to rely on young, homegrown players as opposed to expensive foreign imports.
There are 24 Europa League clashes in total due to take place on Thursday as the likes of Lyon, PSV and Lazio join at this stage of the competition and face Real Betis, Ludogorets, Legia Warsaw respectively.
