Aston Villa boss Unai Emery says his side may have squandered their chances of finishing in the top eight of the Champions League following their loss at Monaco.

Wilfried Singo headed home the game's only goal on Tuesday night as a below-par Villa were unable to convert their opportunities.

Finishing eighth or above in the league phase of the competition ensures direct qualification for the knockout stage and a win for Villa in Monaco would have meant they had one foot in the next stage.

However, the loss means they will likely need to beat Celtic at Villa Park next week to avoid having to go into a two-legged knockout phase play-off.

"When we are playing games like this, it's important to get three points because I think we lost the opportunity to get in the top eight," Emery said.

"Today was the key."

Emery's Watkins and Duran 'challenge' continues

Despite this loss, Aston Villa have been in good form lately, winning seven of their last 12 games in all competitions.

As well as competing in Europe, Villa are also battling for a top-four finish in the Premier League and key to their performances at home and abroad are strikers Ollie Watkins and Jhon Duran.

Watkins has scored 10 goals in all competitions so far this term while Duran has 12 but Emery has mostly opted to rotate the two, having been unable to get them to play effectively as a partnership.

Watkins started against Monaco with Duran joining him in attack in the 57th minute but neither were able to really threaten the hosts before full time.

"The last 20 minutes we played with two strikers and with two strikers we are not being organised with the positioning like I want," Emery said.

"We have two good strikers. Playing with two strikers is my challenge. Both are very good players but today it didn't work well.

"I made a mistake when I decided to play with two strikers. Until that moment we were more or less controlling the game."