Andy Murray came through a tough test against Alexander Bublik to reach the Boss Open quarter-finals in Stuttgart.
Murray let a set and a break lead slip and had to save three set points before fighting past the seventh seed from Kazakhstan 6-3 7-6 (7-4).
The Briton will face either top seed Stefanos Tsitsipas or Switzerland's Dominic Stricker next.
The three-time Grand Slam winner is playing several grass-court events before Wimbledon begins on 27 June.
Having taken the first set with relative ease, Murray broke early in the second before Bublik fought back, winning four games in a row for a 5-2 lead.