After an evenly matched opening half-hour, the Brazilian wing-back brought the game to life, bursting into the Auxerre area and shooting Ajax in front after collecting Rafael van der Vaart's excellent back-heel.
 Ajax had been boosted by the return of captain Van der Vaart from suspension, while young striker Ryan Babel was given an opportunity up front with January signing Angelos Charisteas ineligible. Auxerre coach Guy Roux recalled Bonaventure Kalou and Philippe Violeau, both recovered from injury.
 The match started tentatively with the only goalmouth action in the first 20 minutes provided by Van der Vaart free-kicks, two of which were easily punched clear by Fabien Cool, before the third, from 20 metres, was excellently saved by the Auxerre goalkeeper diving to his left.
 Ajax were dominating possession but were always at risk on the counterattack, as was shown on 33 minutes when Kanga Akalé was brought down by Hatem Trabelsi as he looked to race clear. The Tunisian received a yellow card and watched as the resulting free-kick was placed just the wrong side of the post by Violeau.
 Three minutes later Ajax were in front and it was no surprise that Van der Vaart had a pivotal role. Maxwell raced down the left before playing a lovely give-and-go with the Ajax captain, seeing the ball back-heeled into his path before slamming it high into the net.
 Once in front Ajax burst into life and could have added to their lead before half-time, twice going close through the 18-year-old Babel and a Trabelsi shot from 20 metres. After the break the same pattern continued. The hosts would have been two ahead just four minutes after the resumption had Van der Vaart's curling set-piece deflected off Bacary Sagna's head and into the net, rather than on to the crossbar.
 On 53 minutes, however, Auxerre fired a warning sign that they were still a force to be reckoned with, when an error by Trabelsi allowed Kalou to cross for Benjani Mwaruwari, who saw his header well saved by Ajax replacement goalkeeper Maarten Stekelenburg.
 The visitors began to regain confidence and just past the hour mark went close twice through a dipping Violeau volley and a Benoît Cheyrou drive which was deflected just past the post in a period of good pressure.
 But no French side have won the UEFA Cup, and if Auxerre are to become pioneers they will need to reverse a one-goal deficit in the second leg after failing to capitalise on their only threatening spell. Auxerre's cause may be helped, however, by the condition of Van der Vaart, who was substituted on 78 minutes with what looked like a leg injury.