Manchester United forward Anthony Martial rarely smiles despite regularly having his name sung by the Old Trafford faithful.“I see a great improvement in the person, in the mood, in the face, in the body language – if you want just a word, in the happiness,” said Jose Mourinho of Martial in September. “He’s a happy guy, he’s working extremely well. He starts matches, he tries to do well.“[If] he goes from the bench, even if it is for 10 minutes like in the last [league] match at home, he tries to enjoy and try to give something in these extra minutes. I am very pleased with his attitude overall and then it’s easier to play well.”Martial managed only four Premier League goals last season, leaving fans questioning Mourinho's harsh treatment of the youngster.The 21-year-old Frenchman has been in excellent form this season but was unable to get on the scoresheet in Saturday's 0-0 stalemate away at Liverpool.Mourinho set out his side very defensively and successfully stifled Liverpool's attacking players to maintain United's unbeaten start to the season.Manchester United lie 2nd in the Premier League table, two points behind their 'noisy neighbours' Manchester City.

Smalling's tweet about Martial

Manchester United fans have barely seen the former Monaco wonderkid crack a smile during his two-year stay in Manchester.

That's why a photo ahead of their Champions League trip to Benfica was proving popular on social media.

The tweet featuring Martial, sent from Manchester United's official account had well over 1000 retweets in less than half an hour.

Chris Smalling joined the Man United fans on Twitter in a state of awe at Martial's huge smile.

Martial's secret is out - he does know how to smile!

Competing with Marcus Rashford for a starting berth, Martial has only made five starts but has already netted five times in all competitions this season.

Spirits appear to be high amongst the Manchester United players, despite criticism over their negative performance at Anfield.

The Reds have an 100% record in the Champions League thus far and a positive result at Benfica would all but wrap up their place in the knockout rounds.