Right midfielder: Carlos Soler (Valencia)
Valencia may be languishing in eighth position on the La Liga table with 28 points in 18 games, but without Carlos Soler, it could've been much worse.
The Spaniard has netted seven goals and assisted twice in just 14 games. He has become one of the key figures in Jose Bordalas' squad.
Most of his goals have also come in key moments. He scored their only goal in a 1-0 win over Getafe and a pair of 1-1 draws against Granada and Rayo Vallecano.
In Valencia's final La Liga game of the season before the winter break, he also popped up with a second-half brace against Levante to turn the tide as the Bats won 4-3.
Central midfielder: Casemiro (Real Madrid)
Casemiro offers incredible balance to Real Madrid, often being the nexus between the back-four and their attack.
Intelligent, mobile, aggressive and hard-working, the Brazilian is a pocket dynamite. It's hard to play against him when he's in full swing.
Casemiro is vital in breaking down opposition play with his vision and tackling ability, and has a penchant for popping up with a goal or two.
The 29-year-old averages nearly three tackles a game in La Liga this season, has won 2.8 aerial duels and made three assists.
Left midfielder: Juanmi (Real Betis)
Real Betis have offered a pleasant surprise this season, sitting in third place with 33 points from 18 games. They look like serious contenders for a Champions League place.
Head coach Manuel Pellegrini has run a taut ship with a highly talented squad led by Juanmi, La Liga's rising star.
He's struck 11 times from 16 games. He ended the first half of the La Liga season by scoring at least once in five consecutive games, a run that also included a hat-trick.
On the fringes of the club in his first two years, Juanmi has been a revelation this season. He has established himself as a key figure as Betis look for a top-four finish.