Switzerland survived a nail-biting second-leg World Cup play-off against Turkey to qualify for the 2006 World Cup finals on the away goals rule.
The Swiss appeared to be cruising when Alex Frei converted a second-minute penalty after Alpay Ozalan's handball.
But two first-half headers from Tuncay Sanli and Necati Ates' 52nd-minute penalty revived Turkey's hopes.
Marco Streller's 84th-minute goal eased Swiss nerves before Tuncay completed his hat-trick with another headed goal.
Controversy followed the game when television pictures clearly showed players fighting with each other and officials as they entered the tunnel to return to the dressing room.
Fifa is now set to probe the melee, which was captured on film.
Benjamin Huggel of Switzerland appeared to kick a member of the Turkish staff as he ran from the field, and then Turkey's Alpay, once of Aston Villa, seemed to kick a different Swiss player.
Reports after the game claimed that Stephane Grichting - an unused substitute on the night - had been taken to hospital.
Istanbul's Acidem Hospital and Switzerland coach Kobi Kuhn later confirmed that a Swiss player was admitted for treatment but would give no further details, according to the Anatolia news agency.
Turkey: Demirel, Hamit Altintop, Alpay, Seyhan, Emre (Basturk 82), Penbe, Selcuk Sahin, Sanli, Akin (Metin 70), Ates (Tekke 81), Sukur.
Subs Not Used: Rustu, Balci, Toraman, Halil Altintop.
Booked: Selcuk Sahin, Emre, Seyhan, Penbe, Metin.
Goals: Sanli 22, 36, Ates 52 pen, Sanli 89.
Switzerland: Zuberbuhler, Senderos, Degen (Behrami 46), Spycher, Muller, Barnetta, Wicky, Cabanas, Vogel, Gygax (Streller 31), Frei, Streller (Huggel 87).
Subs Not Used: Coltorti, Vonlanthen, Lustrinelli, Grichting.
Booked: Degen, Zuberbuhler, Behrami.
Goals: Frei 1 pen, Streller 84.
Agg: (4-4) Switzerland win on Away Goals Rule.
Ref: Frank De Bleeckere (Belgium).