They may not be firing on all cylinders just yet, but some of Europe's biggest sides face an early test of form on Tuesday and Wednesday as they aim to avoid disaster in the third round of qualifying for the UEFA Champions League.

Of particular interest will be how two of the Premiership's major players fare. Last season's beaten finalists Liverpool (lost 2-1 to AC Milan) and 2006 runners-up Arsenal (lost 2-1 to Barcelona) are both seeking to claim a coveted place in the group stage.

Other continental powers in action include Sevilla FC, fresh from lifting the UEFA Cup for the second consecutive time last term, and their Spanish compatriots Valencia CF, who will once again be determined to go all the way after losing the final in 2000 and 2001. Four-time winners Ajax Amsterdam (1971, 1972, 1973 and 1995) will be wary of slipping up, as will Portuguese club SL Benfica, who have twice tasted glory in the competition and reached the final on seven separate occasions.

In most cases, the favourites will be conscious that their opponents have more games under their belts at this early stage in the season, having already navigated one or two qualifying rounds. And that could be an especially dangerous factor for the Spanish and Italian sides, who are sure to be more rusty than most as their domestic campaigns have yet to get underway.

The previous rounds failed to throw up too many surprises, although Bulgarian outfit Levski Sofia failed to get past Finnish side Tampere (2-0, 1-0) and will therefore not be making a second straight group stage appearance. Likewise, Belgian League runners-up Genk might have been expected to make it this far but fell to Sarajevo (2-1, 1-0). No such trouble for Rosenborg, on the other hand. These regular UEFA Champions League participants managed to put ten goals past Kazakh team Astana in their two meetings (3-1, 7-1).

Similar scorelines are unlikely in the third round, where the level of competition is best represented by Liverpool's tie against UEFA Champions League newcomers Toulouse FC. The Merseysiders are dreaming of reaching their third final in four years, but their rivals are no strangers to causing upsets, having knocked Diego Maradona's Napoli out of the UEFA Cup in 1986. They also shocked Ligue 1 observers this weekend by registering a 1-0 victory over six-time French champions Lyon, but Liverpool are sure to provide a sterner test after some canny sorties in the transfer market, notably the addition of Fernando Torres to their forward line.

It will also be fascinating to see Arsenal back in Europe for the first time since losing their captain Thierry Henry to Barcelona. The Gunners' trip to Prague to take on Sparta will be a serious examination for a team still waiting for everything to click up front.

This week's other matches are perhaps even harder to call, not least in the case of Lazio, who return to the continental elite after a four-year absence but will have to see off Romanian champions Dinamo Bucharest to advance to the competition proper. Elsewhere, new Red Star Belgrade coach Milorad Kosanovic will not have had too much time to prepare his troops for their tough encounter away to Glasgow Rangers, having replaced Borko Djurovski since the last qualifying round.

The intrigue does not end there either, with Tuesday's encounter between Benfica and Copenhagen reuniting two teams who met in the group stage last year. Likewise, two more experienced European campaigners cross paths in Russia the following day when league leaders Spartak Moscow host Celtic, while Valencia will need to hit the ground running when they face solid Swedish club IF Elfsborg, who go into the game having oiled their wheels in the two previous rounds.


Third qualifying round fixtures

Tuesday 14 August (second leg, 28 August)
Lazio (ITA) - Dinamo 1948 Bucharest (ROM)
Glasgow Rangers (SCO) - Red Star Belgrade (SRB)
Benfica (POR) - Copenhagen (DEN)
Valencia (ESP) - Elfsborg (SWE)

Wednesday 15 August (second leg, 29 August)
BATE Borisov (BLR) - Steaua Bucharest (ROM)
Tampere United (FIN) - Rosenborg (NOR)
Spartak Moscow (RUS) - Celtic (SCO)
Werder Bremen (GER) - Dinamo Zagreb (CRO)
Salzburg (AUT) - Shakhtar Donetsk (UKR)
Ajax Amsterdam (NED) - Slavia Prague (CZE)
Sarajevo (BIH) - Dynamo Kiev (UKR)
Fenerbahce (TUR) - Anderlecht (BEL)
Toulouse FC (FRA) - Liverpool (ENG)
Sparta Prague (CZE) - Arsenal (ENG)
Zurich (SUI) - Besiktas (TUR)
Sevilla FC (ESP) - AEK Athens (GRE)