Real Sociedad are about to face a huge test of their watertight defence. 

The LaLiga club conceded fewer goals than any other team in the Champions League group stage. 

But now they visit a free-flowing Paris Saint-Germain side that boast the attacking threat of Kylian Mbappe. 

Ahead of Sociedad's last 16 clash with PSG tonight, we examine whether they can emerge as dark horses in the competition. 

Enrique respect

PSG manager Luis Enrique is under no illusions as to the challenge his countrymen can pose. 

Speaking before the first leg, he said: "Real Sociedad have a tight defence in the Champions League, they don't give the ball away easily. 

"We have to press them aggressively. They are certainly one of the best teams in the competition. 

"That is why they qualified as group winners. They were in a group with last year's finalists." 

Sociedad finished above Inter Milan in Group D by way of goal difference with both teams boasting an unbeaten record. 

That advantage was built upon brilliant defensive displays. In six games, they only conceded two goals and a measly total of 12 shots on target. 

Three of their four clean sheets came in away games, which included a 0-0 draw at Inter in the final match to clinch victory in the group. 

Aggressive strategy

After that result, Sociedad manager Imanol Alguacil was asked how the feat had been achieved. 

He said: "Having very good players, who go to death with the coach's idea. 

"Then you have to have them in the right position to play and take risks in a stadium like this. 

"A coach is nothing without his players and it shows when your players go to the death with you. 

"I don't think we are aware of what we are doing, of what this team achieves. It will probably take us years to realise what this group is doing." 

Alguacil's side have built the best defensive record in the Champions League based on their aggression and ambition, rather than sitting deep. 

They press extremely high up the pitch and win the ball in attacking areas — which is also the strategy of his opposite number.

Alguacil said: "I know that he is a coach who likes to push high and who likes to take the initiative, which we like to do too." 

Cup run

While Sociedad's Champions League displays have been impressive, they have not been faring so well in LaLiga. 

Their 1-0 home defeat to Osasuna over the weekend was the third successive game in which they failed to score, leaving them seventh in the table. 

Yet their form in the Copa del Rey gives hope for a successful run in the Champions League. 

They drew 0-0 in the away leg of their semi-final against Mallorca, setting up the potential for Alguacil to once again lead his team to the trophy that they won under him in 2019-20. 

Winning the Champions League as well, might be too much to expect but Sociedad would seem to have the ingredients to continue their journey in the competition. 

The starting point is in the city of love on Valentine's Day, where Alguacil will be looking to break PSG hearts.