TURIN (Reuters) - Having battled to break down one of Europe's meanest defences in the quarter-finals, Real Madrid will have to do it all over again when they face Juventus in their Champions League semi-final.

The defending champions took just under three hours to break down Atletico's resistance in the previous round, wining 1-0 on aggregate with a goal in the 88th minute of the second leg.

On Tuesday, they face Juventus who were crowned Serie A champions on Saturday with four games to spare after conceding only 19 goals in 34 games.

Juve's defence has been just as impressive in the Champions League with only five goals against in 10 games and six clean sheets.

However, Juventus are also a more refined outfit than Atletico, less prone to rough-arm tactics and capable of coming out and attacking, depending on the circumstances.

Central defenders Giorgio Chiellini, Andrea Barzagli and Leonardo Bonucci have been playing together for four seasons for both Juventus and Italy, winning four successive Serie A titles.

"I think we have the best defence," Bonucci said ahead of their semi-final first leg against Real.

"We know and understand each other perfectly after playing together for so long."

The question is whether it is good enough to repel a Real Madrid attack led by the prolific Cristiano Ronaldo, who sounded another warning by firing his 25th La Liga hat-trick in a 3-2 win over Sevilla on Saturday.

Juventus will also have to worry about breaking down Real's defence, which has not conceded an away goal in the competition since their 2-1 win at Ludogorets Razgrad on Oct 1, a total of 444 minutes' playing time.

Juventus coach Massimiliano Allegri, who has surpassed expectations in his first season at the club, is happy to accept the underdogs' role.

"Many thought we would be eliminated in the group stage but instead we are facing the reigning champions for a place in the final."