Outsider Renzo Olivo saved two match points before defying the odds to beat top seed Philipp Kohlschreiber and seal his place in the semi-finals of the German Tennis Championships in Hamburg.
Kohlschreiber was the favourite to lift the title on home soil, but world number 153 Olivo upset the Augsburg-born 32-year-old by winning 1-6 6-0 7-5 at the Rothenbaum Tennis Center on Friday.
The 22-ranked Kohlschreiber won the BMW Open in Munich back in May and looked set to move two victories away from another triumph in his homeland when he led 5-3 in the deciding set.
Unseeded Argentine Olivo was not finished yet, though, saving a pair of match points as he won the last four games to send a shell-shocked Kohlschreiber packing.
Olivo, who took six out of seven break-point opportunities, can now look forward to his first ATP World Tour semi-final against compatriot Pablo Cuevas.
Cuevas saw off Paul-Henri Mathieu 7-6 (9-7) 6-1 to keep himself in contention for a third title of the season.
The third seed belted down 12 aces and saved the only break point he faced, while breaking the Frenchman twice to move into the last four.
Stephane Robert booked his first ATP World Tour semi-final for six years by beating eighth seed Guillermo Garcia-Lopez 7-6 (7-4) 4-6 6-3, with Martin Klizan his opponent after the seventh seed ousted Daniel Gimeno-Traver 6-4 6-3.