Harold Solomon has seldom appeared more helpless than he did yesterday on the center court at Foro Italico as top seed Bjorn Borg, emotionless as the grim reaper, cut him down and moved into the senifinals of the Italian Open tennis championships.

Borg is the only current world-class player that Solomon has never beaten. Yesterday the solid and stolid young Swede extended his career mastery to 8-0 in just 57 minutes. The scores were 6-2, 6-1, and from the fourth game there was an air of inevitability about the result that made the match as gray and somber as the leaden skies on a dreary Roman afternoon.

In the only competitive match of the men's quaterfinals, 1976 champion Adriano Panatta beat Victor Amaya, the massive left-hander, 7-6, 6-4.

Panatta had two set points against him on his serve at 4-5 in the first set, but Amaya gift-wrapped and presented them to him amid relieved cheers and applause from Panatta's hometown fans.

In two other quarterfinals pitting an attacker against a defender - John Lloyd vs. Eddie Dibbs and John Alexander vs. Jose Higueras - defenders won, hands down.

Dibbs, the pugnacious 5-foot-7 Floridian, had far too much baseline artillery and stamina for Lloyd, winning 6-2, 6-1. Higueras, the prototype of the steady and patient European clay court specialist, similarly frustrated the aggressive thrusts of Alexander, 6-2, 6-4.

"I'm not really in the same class with Dibbs on clay, but if it had been dry I might have been able to come in and volley some," said Lloyd, whose greatest assets are his fleetness of foot and quickness at the net.

Solomon was simply overpowered and dominated by Borg, so much so that a few bored spectators were reduced, as is their won't during one-sided matches at Foro Italico, to making paper airplanes and sailing them onto the court.

Borg and Solomon play the same style on clay - heavy topspin from both wings, trying to grind down an opponent from the backcourt, run him to exhaustion, pass him when he comes in - but Borg is better at it.

The soon-to-be 22-year-old Swede is bigger and stronger than Solomon. He hits harder. He has more flexibility in his western forehand and two-fisted backhand, a much better volley and a far superior serve.

In short, Borg is one of the few players fit, swift, steady and mentally tough enough to outlast Solomon in trench warfare from the backcourt, and he has more options. The effect of this is devastating on the 5-6, 138-pound "Little big man."