Defending champion Italy advanced to the semifinals of this year's Davis Cup international tennis competition today when Corrado Barazzutti upset Manuel Orantes, 7-5, 7-5, 6-1, to give the Italians an unbeatable 3-1 lead in the best-of-five European Zone B final series.

Spain's Javier Soler made the final score 3-2 by beating Italian No. 1 Adriano Panatta, 6-1, 6-0, in a meaningless match that was reduced from the traditional best-of-five sets to best-of-three by agreement of the team captains. Panatta's lackadaisical play incensed the crowd and sparked several incidents.

Panatta showed little inclination to fight and lost in barely more than half an hour to a player who is not in his class.

The crowd of 6,000 booed the italian ace, who appeared to deliberately hit some shots out, and showered the court with cushions. Some spectators tried to attack Panatta as he left the court, and fist fights broke out between Spanish and Italian partisans.

Barazzutti, playing cautiously, took 2 hours 40 minutes to overcome an erratic Orantes, who only returned to competition two weeks ago after undergoing surgery on his left elbow. Orantes double-faulted to lose the first set and had little consistency after playing his best tennis of the match early in the second.