Amsterdam, Aug. 14 -- Last season's Champions League semifinalist Ajax came close to crashing out in qualifying Tuesday, coming from behind to beat PAOK Thessaloniki 5-4 on aggregate.

On a night when former European champions Porto and Celtic were both knocked out, Ajax faced elimination when its former youth player Diego Biseswar scored for PAOK in the 23rd minute to put the Greek team 3-2 ahead on aggregate.

Ajax captain Dusan Tadic saw one penalty saved, but scored a second to draw level. A Nicolas Tagliafico header finally put the Dutch team ahead in the 79th, before PAOK's rough, physical style handed Ajax a third penalty converted by Tadic.

Biseswar scored again in stoppage time for PAOK to again put Ajax in danger, but the Dutch...