Nigerian-born Polish national Emmanuel Olisadebe and Michalis Constantinou grabbed a goal each Wednesday night to give Panathinaikos a 2-0 win over Schalke and advance to the next phase of the Champions League. With only one game left in the first round, Panathinaikos piled up 12 points to ensure first place in Group C and repeat last season’s record in Europe’s most prestigious soccer tournament. Arsenal, with nine points, also advanced to the final 16, after a 3-1 win over Mallorca in London. The Spaniards have six points, while Schalke remains last with three. The two clubs will now fight for a place in the UEFA Cup. Olisadebe leaped past a German defender in the 31st minute to head home Panathinaikos’s first goal, off a free kick from Giorgos Karagounis. It was his second straight goal in two Champions League games. He netted the consolation goal last week, when Panathinaikos lost 2-1 to Arsenal. In Wednesday’s game, Panathinaikos’s keeper, Antonis Nikopolidis, made two awesome saves to shots from Marc Wilmots and Ebbe Sand, and another to a blistering free-kick from 30 meters by Tomasz Hajto. Schalke stepped up its attacks after the rest period but never threatened Nikopolidis. Instead, with a fast break in the 60th, Michalis Constantinou made it 2-0, slotting home a shot from the edge of the box. In the last 10 minutes of the match, played before a sellout crowd of 13,000 spectators at the Apostolos Nikolaidis stadium, the Germans besieged the Greek area. But the sturdy Greek defense checked all attacks.