A half-eaten ham sandwich tossed from the stands may have cost Mark Koevermans his match against Alberto Mancini and a place in the quarterfinals of the Italian Open.

With Koevermans leading 5-4, 30-15 in the decisive third set Thursday night, the 23-year-old Dutchman fired a hard first serve to Mancini's backhand.Rushing the net on the service return, Koevermans placed a forehand volley to the far corner. Scrambling, Mancini chased the ball down and batted a weak shot that Koevermans fired down the line for an easy winner, and apparently two match points.

But a spectator at the Foro Italico had tossed the sandwich onto center court at the end of the point. According to umpire Richard Ings, it had interfered with Mancini's ability to play the ball.

Ings ruled the point a let. Koevermans went on to lose the point, his serve, and eventually the match 6-0, 4-6, 7-6 (7-1).

"It's a judgment call," ATP supervisor Gayle Bradshaw said today. "If the umpire believes that the object impeded Mancini from hitting his shot, he has to call a let."

Koevermans was not of the same opinion, claiming that the sandwich had landed well after Mancini had hit his last shot. And a television replay seemed to support his case.

"It's an unfortunate incident," Bradshaw said. "Unfortunate that this person in the stands decided that he had to become a part of the match at such a crucial time. But since it's not a ruling dispute but a judgment call, Koevermans cannot appeal."

Koevermans limited his protests to a short discussion with Ings. Earlier in the match, during a pause in play while Koevermans was rallying from a 4-2 deficit in the second set, another fan had tossed an apple onto the court.