Although Madrid did substitute that league game with a friendly against Getafe, which they won 6-0, that remains their only match ahead of the new season, making it hard to draw conclusions over the match fitness of Zidane's men.
The GFA is yet to officially respond to the purported resignation of its deputy general secretary. Enditem
Duisburg tried to keep pace but the "BVB" continued their relentless march, as Giovanni Reyna's deflected free-kick left goalkeeper Leo Weinkauf helpless five minutes into the second half.
The new season is said to be Lucien Favre's last chance to turn things around after the side failed to overtake their high-spending Bavarian rivals in the past two years.
Coach Ronald Koeman had told the player, who turned 21 a month ago, that he didn't want him this season. Speaking after the game, which Barca won thanks to a solitary Antoine Griezmann goal, Koeman implied that the youngster would indeed be on his way out.
Slovan's Brazilian striker Rafael Ratao had the biggest opportunity in the 41st minute when he found himself one-on-one with the goalkeeper but failed to take the clear-cut chance, instead, failing to square the ball to a teammate.
Raul Jimenez put the away side in front with a half-volley from Castelo Podence's left-wing cross, before Romain Saiss's header from Neto's corner completed the scoring.
"The situation was complicated so it was important to win tonight. It's hard, we created some chances, but we're not 100%."
Club officials said the number of fans must be manageable.
Freiburg seems in trouble as the brave-hearts have not only lost their goalie Alexander Schwolow (Hertha), defender Robin Koch (Leeds) and striker Luca Waldschmidt (Benfica).
Teda rank in the bottom in the Suzhou division with an embarrassing no-win record. Enditem