New Delhi, Aug. 11 -- LONDON - Konstantinos Karetsas had been a Borussia Dortmund player for three days when he picked up the ball inside the Arsenal penalty area on Saturday, turned onto his left foot, and curled a shot that clipped the post and finished in the net. The 21-year-old Belgian playmaker scored, on debut, against the club that had spent the summer in contact with his representatives.

Arsenal, the reigning Premier League champions, lost 3-2 to Borussia Dortmund in the Emirates Cup and walked away with an uncomfortable set of questions for the twelve days before their title defense begins. Defensive disorganization, punished three times at the Emirates Stadium, was harder to explain away than a bad day or an unfamiliar lineup....