Jens Toornstra handed the Dutch side a 56th-minute lead in their Group G clash and the hosts soaked up waves of pressure before El Ahmadi's dipping long-range effort sealed a 2-0 win.
HNK Rijeka triumphed by the same scoreline to eliminate Standard Liege, meaning Sevilla must avoid defeat in their final round-robin match against the Croatian team to progress.
Everton's Belgium international duo Romelu Lukaku and Kevin Mirallas netted on the counter-attack to overturn a largely impressive Wolfsburg 2-0 at the Volkswagen Arena and seal top spot in Group H.
Lille drew 1-1 with bottom side Krasnodar, and Wolfsburg will join Everton in the round of 32 if they can avoid defeat to the Ligue 1 outfit next time out.
Progress was not so emphatic for another of the tournament's fancied teams, Napoli, but a goalless draw at Sparta Prague did the job in Group I.
Inter made returning coach Roberto Mancini sweat for a 50th birthday win as they came from a goal down to beat Dnipro 2-1 and nail down first place in Group F.
The visitors moved ahead through Ruslan Rotan and Yevhen Konoplyanka missed a penalty two minutes before Zdravko Kuzmanovic's equaliser.
Dinamo Moscow and Fiorentina were already through from Groups E and K respectively and continued their fine form with 2-1 wins over Panathinakos and Guingamp.
First place is still up for grabs after Tottenham beat Partizan 1-0 on a bizarre night at White Hart Lane where three first-half pitch invaders forced the teams to leave the field. Benjamin Stambouli got the winner after the action resumed.
Besiktas must beat Tottenham to take top spot having let a two-goal lead slip in a 2-2 draw at Asteras.
Borussia Monchengladbach shared the same scoreline with Villarreal in Group A - Granit Xhaka's equaliser for the Bundesliga team standing as the highlight of a pulsating contest.
Alan's early brace set Group D winners Salzburg on their way to a 3-1 triumph at Celtic, although their opponents will join them in the last 32 after Dinamo Zagreb lost 1-0 to Astra.
That result meant an end to Lokeren's involvement, despite Hans Vanaken's early strike sealing a 1-0 win that saw the Belgian outfit end Legia's 100 per cent record.
A dramatic winner deep into stoppage time from Macoumba Kandji gave HJK Helsinki a 2-1 win over Copenhagen to keep Group B wide open.
The Finnish team will now travel to leaders Brugge, who are three points better off thanks to a stunning individual performance by goalkeeper Matthew Ryan in a goalless draw against second-placed Torino.
