Ajax had to rely on sought-after midfielder Christian Eriksen to grab a 3-3 draw at Heerenveen after the champions blew a two-goal lead.
Eriksen struck in the 65th minute after the Amsterdammers had threatened to throw away all the points.
Goals from Niklas Moisander (13) and Kolbeinn Sigthorsson (17) suggested an easy night was on the cards but by half-time the game had turned completely.
Alfred Finnbogason levelled matters with a quickfire double before Magnus Wolff Eikrem sent Heerenveen ahead a minute before the break.
Ajax lost 3-2 on the opening day at AZ Alkmaar and Eriksen at least ensured there was no repeat as he netted his second of the season.
Aarhus recorded their third win in six Superliga games with a 3-1 home success against Sonderjyske.
Hallgrimur Jonasson gave the visitors a third-minute lead but Hjalte Bo Norregaard equalised with just seven minutes on the clock.
Soren Larsen then struck twice in four second-half minutes to earn Aarhus a win which lifts them to second in the table, though the teams closest behind them are all still to play this weekend.
Turkish Super Lig
Genclerbirligi claimed their first win of the new Super Lig season with a 3-0 thumping of Akhisar Belediye.
Jimmy Durmaz (17) and Ermin Zec (33) gave the hosts a 2-0 half-time lead before Bogdan Stancu completed the scoring three minutes fom full-time.
Akhisar Belediye opened the season last weekend with a 3-1 win over Elazigspor.