The result kept the league leaders on course for a record 24th title, although second-placed Parma cut their advantage at the top to five points by winning 2-1 at Perugia.
Boksic was dismissed in the 77th minute for hitting the Inter defender Massimo Paganin just 10 minutes after coming on as a second-half substitute.
Inter almost broke the deadlock after only seven minutes, when Maurizio Ganz knocked the ball in. He was clearly offside but the referee at first gave a goal before changing his mind.
Parma fell behind in the 11th minute, but within a minute, the Argentinian Hernan Crespo equalised with his third goal in two matches and five minutes later Massimo Crippa scored the winner from the edge of the area.
Sampdoria's faltering title challenge suffered a devastating blow in Bergamo, where they encountered the league's leading scorer, Filippo Inzaghi, in prime form. The Atalanta striker ran rings around Sampdoria's suspect defence to claim a hat-trick and take his season's tally to 18.
Napoli fans greeted Milan's coach, Arrigo Sacchi, by throwing a black rubbish bag on to the pitch. It proved a fitting gesture - the match was a dull, scoreless draw that left the champions languishing in 12th place.
Bayern Munich were knocked off the top of the German championship by Bayer Leverkusen, who thrashed them 5-2 yesterday with Markus Feldhoff scoring a hat-trick. The result enabled Borussia Dortmund to finish the weekend back on top of the table on goal difference after their 2-1 victory over Freiburg.
Leverkusen exposed huge holes in the Bayern defence, going 3-0 up through the Brazilian Paulo Sergio, Rene Rydlewicz and Feldhoff. Bayern fought back with goals by Christian Nerlinger and Mario Basler, but Feldhoff struck twice in the last 10 minutes to complete his hat-trick.
In the Netherlands, Feyenoord and PSV Eindhoven played out a tense 0- 0 draw in Rotterdam, leaving PSV still three points clear in the Dutch league.
An under-strength PSV will leave Feyenoord's de Kuip stadium the more satisfied, but the match extended Feyenoord's unbeaten home record against PSV to 11 matches.
Paulo Cesar Wanchope, the striker who has just signed for Derby, scored a first-half hat-trick to help Costa Rica to a 5-0 victory over Cameroon in friendly match in San Jose.Reuse content