Arsenal fell behind at Meadow Park to Scotland international Caroline Weir's goal just before half-time, but Russo rescued the Gunners with a pair of second-half headers.

Russo looped a header over Madrid goalkeeper Misa Rodriguez to bring Arsenal level and then headed in the winner from a corner to end the Spanish side's unbeaten record in the competition.

United slid to a 5-2 loss at Wolfsburg as Dutch internationals Ella Peddemors and Lineth Beerensteyn both struck twice.

Fridolina Rolfo headed United in front in Germany as Marc Skinner's team began well in their search for a fourth successive win in Europe.

However, Wolfsburg equalised through Peddemors after a poor clearance from goalkeeper Safia Middleton-Patel.

Peddemors netted again with a cross that found its way in after eluding several players before Beerensteyn rifled in from distance to double Wolfsburg's lead.

Melvine Malard's lob got United back into the game just before half-time but Beerensteyn effectively secured the win for Wolfsburg with her second goal of the night.

Vivien Endemann added a fifth deep into stoppage time for Wolfsburg as they won for the third time in four matches.

"We had a good start, so we were hoping that it would be our game, but it was definitely not," Rolfo told UEFA.com

"We'll have to analyse this game and learn from it, because this is not how we want to play."

The Germans moved above United on goal difference into third in the standings with two rounds of matches to play. The top four teams qualify directly for the quarter-finals.

"That we started the Champions League very well is the positive thing at the moment," added Rolfo.

"We, of course, want to go far. Now we have two more games in the league phase. We have to give it our all and hopefully win both of them."

Lyon sit top of the standings after producing an extraordinary fightback capped by captain Wendie Renard's 90th-minute penalty to earn a 3-3 draw with Juventus.

The Italian side looked to be cruising after goals from Chiara Beccari, Michela Cambiaghi and Tatiana Pinto in the first half gave them a 3-0 lead.

But Tabitha Chawinga pulled one back for Lyon on the hour and Marie-Antoinette Katoto grabbed another before Renard converted from the spot to snatch a point and keep the record eight-time European champions unbeaten.

Lyon have 10 points and are one clear of Barcelona, Wolfsburg and United.

Barcelona visit Chelsea on Thursday, with both sides vying to take over top spot. Chelsea have seven points from their opening three matches.

Paris FC picked up their first win as they beat 10-woman Benfica 2-0 in the French capital.

St Poelten snapped a run of three successive defeats as they came from two goals behind to draw 2-2 at Valerenga to register their first point in the competition.