Tipsarevic vanquished wild card entry Ernests Gulbis 6-3, 6-4 and will meet Aliaz Bedene of Slovenia in a Friday quarterfinal match. Germany's Haas beat Canadian-born American Jesse Levin 6-4, 6-2 and and will play Grega Zemlja in the quarters on the indoor hardcourts at Wiener Stadthalle.
Bedene downed American Donald Young 7-6 (7-4), 6-7 (2-7), 6-3 Thursday to advance and Zemlja beat Australian Matthew Ebden 7-5, 6-4.
Marinko Matosevic took out wild card Austrian Dominic Thiem 6-3, 7-6 (7-5) in a second round match and Paoloa Lorenzi beat Canadian qualifier Vasek Pospisil 6-4, 6-4.
Juan Matin del Potro meets Matosevic and Gilles Muller of Luxembourg plays Lorenzi in other quarterfinal matches.