Retired Real Madrid midfielder Toni Kroos responded to former Barcelona attacker Arturo Vidal's claim that he taught the game to the German. The two were teammates at Borussia Dortmund for two seasons.Kroos is widely regarded as one of the finest midfielders of his generation, spending a hugely successful decade-long spell with Los Blancos. Since arriving from Bayern Munich in the summer of 2014, the 35-year-old scored 28 times in over 450 games and won a slew of big titles.The former Bayern man, renowned for his stout presence in the middle of the park, won four La Liga and five UEFA Champions League titles among other domestic and continental honours before announcing his retirement last summer.Vidal - who played with Kross at Dortmund in 2008-09 and 2009-10 - acknowledged Kroos' quality but claimed that the German didn't have the 'touch' and that he taught Kroos 'a lot':“Toni Kroos learned a lot from me," Vidal said (as per Madrid Zone). "He was good technically but lacked the touch. He came to me & Renato Augusto, and we explained him what football was like — we taught him a lot.”Kroos responded to the comments with three crying face emojis.Vidal would go on to play for top clubs like Bayern, Barca, Juventus and Inter Milan. He currently plays for Colo-Colo in his native Chile.How have Barcelona and Real Madrid fared this season?Barcelona boss Hansi FlickBoth Barcelona and Real Madrid have had decent starts to the season. While Los Blancos are top of the La Liga pile with six wins out of six, the defending champions are two points adrift in second, winning five of six games.It's been a superb start to life for new Los Blancos boss Xabi Alonso. After guiding his side to the FIFA Club World Cup semi-finals in the United States, the Spaniard has become only the second manager to win his first six La Liga matches in charge of the capital club.In their most recent outing, Real Madrid won 4-1 at Levante, thanks to a Karim Benzema brace, to remain clear at the top as Alonso joined Vanderlei Luxemburgo as the only man to win their first six La Liga games in charge of Madrid. Los Blancos next take on Atletico Madrid away in the league on Saturday (September 27), where Alonso could claim the record outright.Meanwhile, Barcelona are also unbeaten this season, with both them and Madrid winning their respective UEFA Champions League openers.