Arsenal will launch the defence of their Champions League crown on Tuesday night with a game in the new-look format against eight-time winners Lyon.
The north Londoners overcame Barcelona in Lisbon in May to claim the crown for the first time in the last game of the competition under the old group stage format.
From Tuesday, the initial phase of European club football's most prestigious tournament becomes an 18-team league.
Clubs will play six matches – three at home and three away – and the top four will qualify automatically for the quarter-finals in a configuration similar to the men's competition..
The sides that finish fifth to 12th will advance to a two-leg knockout play-off round to decide the four other last eight spots.
On their way to glory last season, Arsenal overcame Lyon 5-3 on aggregate but they go into the game at Meadow Park just outside London struggling for success.
Saturday's 3-2 defeat at Manchester City followed draws against Manchester United and Aston Villa in the English Women's Super League.
"When we have momentum, capitalise, be ruthless and protect yourself really well for when the momentum shifts again," said Arsenal boss Renée Slegers after Saturday's defeat to Man City.
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Lyon roaring in French championship
Lyon go into the clash in rude health. They sit top of the Arkema Première League in France with four victories from their four games in which they have scored 19 goals.
A 6-1 annihilation of Paris Saint-Germain on 28 September was followed by a 8-1 mauling of Lens a week later.
"I'm very happy," said Lyon head coach Jonatan Giráldez. "We had the opportunity to make a lot of changes between the last two matches and the players responded excellently.
"The whole team is fully committed and motivated to maintain this level, which is essential in order to prepare well for the Champions League. It's a real boost for the team's confidence."
Last season's runners-up Barcelona host Bayern Munich also on Tuesday while on Wednesday, PSG travel to Wolfsburg in Germany and the WSL champions Chelsea visit the Dutch side Twente.
