The second-seeded Wawrinka stopped after a medical timeout more than 2 hours into his match with Feliciano Lopez, who was leading 6-4, 2-6, 4-3.
The 10th-ranked Wawrinka has won only five matches — all against players outside the Top 50 — in seven visits since reaching the 2005 final of his home tournament.
The fifth-seeded Lopez will face Robin Haase of the Netherlands in the clay-court tournament on Saturday. The 57th-ranked Haase beat 2011 champion Marcel Granollers of Spain 5-7, 6-3, 7-6 (5).
The sixth-seeded Russian saved three match points in the tiebreaker.