Analysis: Four things we learned from Spain's Matchday 17

MADRID, Dec. 13 (Xinhua) -- Real Madrid's win at home to Atletico Madrid in the city derby on Sunday night means that Carlo Ancelotti's side have effectively knocked the reigning Champions out of the title race, while Real Sociedad have also fallen by the wayside and FC Barcelona are in danger of humiliation. Here are some things we learned in LaLiga this weekend.

1 Firepower makes all of the difference for Real