Ajax face an uphill task to reach the last four of the UEFA Cup after the Dutch club were beaten 3-1 at home by Spartak Moscow.
Striker Alexander Shirko scored in the 26th and 52nd minutes to put the Russian champions 2-0 ahead.
Ajax's hopes were briefly restored when Georgian Shota Arveladze swept the ball home in the 57th minute after good work by Nigerian winger Tijani Babangida.
But Spartak added the third against the run of play when Valery Kechinov beat goalkeeper Edwin van der Saar with a low shot with six minutes remaining.
Both Italian clubs won 1-0 at home, Ronaldo scoring for Inter Milan against Schalke 04 and Pierluigi Casiraghi giving Lazio victory over Auxerre.
Lazio were reduced to 10 men shortly after scoring when Yugoslav international Vladimir Jugovic was sent off.
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