Wozniacki was leading 6-2, 2-2 when Paszek was forced off.
The Austrian, who was chasing her first win on the WTA tour since January, was broken at 3-2 and Denmark's Wozniacki then broke again to take the opening set. Paszek broke to lead 2-1 in the second set but then received treatment, lost her next service game and retired.
A single break of serve late in each set gave Australia's Bernard Tomic a 6-3, 6-4 victory over British wild card James Ward.
Results from the second day of the ATP-WTA Eastbourne International (x denotes seeding):
Men:
First round:
Bernard Tomic (AUS) bt James Ward (GBR) 6-3, 6-4
Feliciano Lopez (ESP) bt Jarkko Nieminen (FIN) 7-6 (7/3), 7-6 (7/5)
Martin Klizan (SVK) bt Victor Troicki (SRB) 6-3, 6-2
Ivan Dodig (CRO) bt Denis Istomin (UZB) 6-3, 6-4
Radek Stepanek (CZE) bt Marinko Matosevic (AUS) 6-3, 6-2
Julien Benneteau (FRA) bt Kevin Anderson (SAF x5) 7-6 (7/4), 6-2
Women:
First round:
Hsieh Su-Wei (TPE) bt Johanna Konta (GBR) 6-4, 6-3
Lucie Safarova (CZE) bt Klara Zakopalova (CZE) 6-4, 7-6 (7/3)
Angelique Kerber (GER x3) bt Sorana Cirstea (ROM) 6-4, 6-4
Caroline Wozniacki (DEN x5) bt Tamira Paszek (AUT) 6-2, 2-2 retired
Elena Baltacha (GBR) bt Kristna Plskova (CZE) 7-5, 7-6 (7/3)
Petra Kvitova (CZE x4) bt Monica Niculescu (ROM) 6-4, 6-1
Li Na (CHN x2) bt Alize Cornet (FRA) 6-2, 6-4
Elena Baltacha (GBR) bt Karolina Pliskova (CZE) 7-5, 7-6 (7/3)
Ekaterina Makarova (RUS) bt Olga Puchkova (RUS) 6-3, 6-0
Laura Robson (GBR) bt Yuliya Beygelzimer (UKR) 6-3, 6-2
Samantha Stosur (AUS) bt Nadia Petrova (RUS x8) 6-2, 6-3
Jamie Hampton (USA) bt Agnieszka Radwanska (POL x1) 7-6 (7/2), 6-2