4 unheralded players who will play crucial roles in the semi-finals

While the familiar stars sparkle for all four teams taking part in the Champions League semi-finals over the next two weeks, it would be well worth your time to occasionally take your eyes off them, and focus your attention on those who typically fly under the radar.

Here are four players who fit that bill, and who will play massive roles in determining if their respective sides will be travelling to Cardiff next month.

Real Madrid - Dani Carvajal

Has a player rocketed to prominence for both club and country with such little fanfare? The first-choice right-back for both Real Madrid and Spain, 25-year-old Carvajal mixes aggression and defensive solidity with an undiscussed ability to venture forward - his eight assists in all competitions this season are a testament to that.

And yet he continues to be overlooked in discussions about the world's best full-backs.

Much of that has to do with a certain afro-clad teammate; Carvajal, solid as he is, is not even the best full-back in his own XI. Certainly, he's the least flashy of the two, thanks to the presence of Marcelo, who has been an absolute monster for Real Madrid this season, dominating the left flank and, oftentimes, the centre of the pitch by cutting inside and creating chances at will for his teammates - while also scoring his share of goals.

Carvajal, meanwhile, just goes about his business. There's little flair, though he's proven that he's capable of that, too, on occasion. For a team that can be dangerously unbalanced at times, the little Spaniard's role as a steady, dependable cog in the machine is vital.

The majority of that is down to his own skill set, though some of it is simply because his understudy, Danilo, is a liability, and has the defensive prowess of a wet paper bag.

Carvajal is an integral part of Zinedine Zidane's side.

Atletico Madrid - Stefan Savic

Diego Godin is the heralded veteran and Jose Gimenez the presumed heir, but equally as important to Atletico's success - and arguably more so than the younger Uruguayan - has been Savic.

The Montenegrin, 26, has established himself as a favourite of manager Diego Simeone, starting 35 matches this season at the heart of the Rojiblancos backline. Godin is the first name on the team sheet when fit, and, after a rough start to life in the Spanish capital after his opulent move from Fiorentina, Savic has proven to be equally important.

Often considered rash and prone to boneheaded mistakes earlier in his career with both the aforementioned Italian club, and Manchester City before that, Savic has worked to clean up his game, and now plays a crucial role in helping to maintain Atletico's status as a defensive juggernaut.

Part of that improvement is the system, sure, but his standing above the highly touted Gimenez in the pecking order tells you everything you need to know about just how much Simeone both relies on, and trusts, Savic.

AS Monaco - Kamil Glik

It's impossible not to be enamored with Monaco's crop of attacking talent. The speed, the youthful exuberance, the ruthlessness. It's a treat to watch. But while Radamel Falcao's renaissance and Kylian Mbappe's explosive coming-out party have soaked up the headlines, the play of Polish anchor Glik has been relegated largely to the fine print.

Such is the life of the centre-back - especially one on a team that is going toe-to-toe with Barcelona for the title as Europe's most high-scoring side.

Arriving at the Stade Louis II from Torino last summer in a deal rumoured to be worth around €11 million, Glik came with a reputation as an uncompromising defender who could chip in with goals of his own thanks to his aerial prowess from set pieces. He's proven adept at both ends, allowing Leonardo Jardim to let his young stars loose and play expansive football, while also getting in on the fun himself - the 29-year-old has scored six times in Ligue 1 this season, more than any other defender in France's top flight. Half of those tallies have come via his cranium.

An imperious figure for a stout Polish side at Euro 2016, Glik will need to be at his very best if he's to shut down the familiar faces of Paulo Dybala and Gonzalo Higuain, two men he knows well from his time in Serie A.

Juventus - Mario Mandzukic

It's not just the defenders who fly under the radar.

Though, in fairness, Mandzukic's greatest contributions to Juventus this season have all been of the variety that would suit any of his three predecessors on this list.

Pointy and gangly, yet powerful, the big Croatian executes his defensive duties with the tenacity of a dog playing tug of war. Since being asked to shed his identity as a striker and shift out to the left wing in Max Allegri's 4-2-3-1 formation, the tireless veteran has become indispensable to Juventus' success.

A hallmark of the Bianconeri's victory over Barcelona in the quarter-finals was seeing Mandzukic chase down Lionel Messi, harry Ivan Rakitic, and make life miserable for Sergi Roberto.

He's as likely to turn up inside his own penalty area, making a tackle or winning a header, as he is to create an opportunity at the other end.

Plenty of eyebrows were raised when Allegri threw a man who had known nothing but the life of a centre-forward throughout his career into an unfamiliar, and physically demanding, position. It's worked a treat thus far, and with Monaco boasting the likes of rampaging full-back Djibril Sidibe and dribbling wizard Bernardo Silva down the right wing, Mandzukic will need to be at his industrious best to help slow them down.