You think they showed a lack of physical fitness
Their season started in August, the whole Spanish team played about 60 matches throughout the season, in the case of most of them, they will have been considered too important to rest and played every match, 2 times a week 90 minutes. THey then went had a 2 week break and then on to the world cup. There once again, most of them played every match every minute and tbh they didnt rest up at all, but kept it going for the 90 minutes again.
+ people like iniesta xavi are 170 cm tall, but yet they have no problem holding off vastly bigger and stronger opponents. They also have no problem playing a whole season at peak form, and running round none stop for 90 minutes, then doing the whole thing again 3 days later. Repeat this cycle for 1 year, and still no fatigue.