De Jong was announced as the new signing during the pre-season friendly of FC Porto against Atletico Madrid.
Ajax had a 9-point lead over PSV with 6 matches remaining at one point in the league, but a series of losses and draws in the subsequent games, meant that PSV were able to close down the deficit and eventually clinch the title.
Arsenal thumped PSV Eindhoven 7-1 at the Philips Stadion in UCL Round of 16 first leg, to take more than a step forward to making the quarter-finals of the competition.
The game ended 2-0 in Eindhoven’s favour, but Sevilla managed to register a 3-2 aggregate win and qualify for the Round of 16.
The clash between Arsenal and PSV on October 20 has resulted into the postponement of the Premier League fixture between Gunners and Manchester City.
Arsenal were scheduled to host PSV Eindhoven at the Emirates Stadium on Thursday, September 15.