Ronaldo Guiaro powered in a header eight minutes from time to leave the Inönü stadium in raptures and Besiktas JK on course to qualify from Group G after victory against AC Sparta Praha.
The Brazilian rose unmarked to knock in a pinpoint cross from Sergen Yalçin just when it had begun to appear that a determined Sparta side would hold out for a point.
The two sides had produced a compelling game on Matchday 3 when Sparta emerged 2-1 winners, but neither could match the heights of that night in a quiet opening period. Libor Sionko shot straight at Óscar Córdoba in the Besiktas goal on seven minutes after a bright start from Sparta, but after that they were content to sit back and look to strike on the break.
Besiktas take initiative
In contrast, Besiktas, who started the match bottom of the group on three points, one less than their Czech rivals, looked to take the initiative and in Ronaldo Guiaro had a player capable of turning defence into attack. On 15 minutes he picked out Kaan Dobra's run, but the Polish international, clean through on goal, shot wide from five metres.
Besiktas had at least upped the tempo and moments later Ilhan Mansiz, back after suspension, narrowly missed as he dived to connect with Daniel Pancu's left-wing cross. Slowly the the game opened up and on 26 minutes Ilhan broke clear of his marker, Petr Johana, only to be pulled back by the defender. Johana was booked and will now miss the crucial visit to Chelsea FC.
Besiktas were beginning to find some room behind the Sparta defence, but still clear chances were hard to come by. On 27 minutes, Dobra shot powerfully from the edge of the area, but straight at Blazek, then Ilhan worked a close-range shooting chance only for Johana to slide and block brilliantly.
Sparta were looking to Karel Poborský and Lukáš Zelenka for inspiration and the pair combined on 30 minutes, the latter cutting to the line then pulling the ball back for the veteran Czech international who shot wide.
Ilhan comes close
There was still time for Pancu to shoot powerfully at Blazek before the end of the half, after which the home side pushed forward again. On 53 minutes Ibrahim Üzülmez crossed for an unmarked Ilhan to head goalwards from three metres but without the power to trouble Blazek. Then the striker latched on to a soft backpass from Vladimir Labant and rounded Blazek only for his shot to be cleared off the line.
Besiktas coach Mircea Lucescu paced the touchline, the frustration clear on his face as he considered his options on how to break down a dogged Sparta defence. On came Ahmed Hassan, but the story remained the same, Blazek stretching on 70 minutes to keep Federico Giunti's cross from reaching the Egyptian striker as he waited to pounce at the far post.
Finally the breakthrough came. Yet another corner was cleared by Sparta but this time it was played back into the box to Sergen Yalçin who looked up and crossed for Ronaldo Guiaro who, standing on the goalline, headed in.
What relief in the Inönü stadium - an already boisterous crowd raised the volume still further, now knowing that, with Chelsea FC having beaten S.S. Lazio, Besiktas were now second in the group and well aware that a point in Rome on Matchday 5 would leave them close to qualification.