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Marek Saganowski looked to have won the game for Guimaraes with a perfect diving header in the 86th minute.

But Vaz Te, on as an 87th-minute substitute, made an immediate impact, hammering a right-footed shot past Paiva after El-Hadji Diouf's set up.

Bolton know victory against Sevilla in their final group game on 14 December will guarantee their progress.

The dramatic ending to the match was somewhat at odds with a match which offered very little in the way of goalmouth incident.

Bolton took 75 minutes to fashion their first shot on goal, and Guimaraes were hardly more incisive.

Nevertheless, the home side looked the slicker outfit in the opening stages - perhaps surprisingly for a side languishing third from bottom in the Portuguese Liga.

What a goal, what a substitution! From DM Have your say on 606

But their attacking play was limited to a couple of long shots from Saganowski and one from Sebastian Svard - and Jussi Jaaskelainen saved comfortably from all of them.

Indeed, for all their industry, the Portuguese side were thankful on 32 minutes when Kevin Nolan almost gave Bolton the lead.

The skipper neatly juggled the ball after Abdoulaye Faye's flick on, and he prodded it inches wide past the despairing dive of goalkeeper Paiva.

Nolan was Bolton's brightest spark in the first half, and a testing cross four minutes before the break caused problems in the Guimaraes defence, although the home team cleared.

After the break, lively substitute Diouf caused problems with a low cross and Nolan fired a shot on the turn into the side-netting with Paiva diving.

Stelios Giannakopoulos forced the first real save towards the end as he broke forward and fired in a low drive which Paiva gathered at the second attempt.

But the real drama came late on.

Bolton's defence, which had kept five clean sheets in a row, had barely looked like being breached.

But Saganowski converted his first clear chance as he pulled free of his marker and converted Tiago Targino's cross.

It looked all over for Bolton, but 19-year-old Portuguese youngster Vaz Te - who had been on the field for just over one minute - latched on to Diouf's knockdown to rifle an unstoppable shot into the corner.