The Argentine was forced to take the scenic route against his talented German opponent, but he found a way to maintain his winning habit. The 29-year-old is now unbeaten in his last nine outings and he will take on Milos Raonic in the semi-finals on Saturday.
Kohlschreiber contributed to an entertaining spectacle, however he was found wanting in the closing stages once again.
The veteran has managed to drag Top 10 opponents into a deciding set on 38 occasions, but his inability to apply the finishing touches has been a reoccurring theme throughout his career.
The German has won just seven of his elongated battles with the elite, and his engaging scrap with the Argentine was yet another near miss.
The 34-year-old used his variety to great effect in the opener – and he capitalised on his rival’s lacklustre start. The 2009 US Open champion took time to warm to his task and he conceded the first set without finding his groove.
The Argentine was in a similar predicament against Leonardo Mayer in the previous round, and he rose to the challenge once again. A punishing forehand from the No.6 seed extracted an error from the German and earned him a 5-3 second set advantage.
Kohlschreiber displayed his shotmaking skills in the following game as he attempted to prevent his opponent from levelling the match, but his best efforts were in vain. Del Potro saved a break-point before ensuring further drama would unfold.
The deciding set proved to be a fitting finale to a high calibre affair. Both competitors played well at the same time and the baseline exchanges reflected the talent on show.
The German clung on to his delivery after a 12-minute game to move 2-1 ahead, but he could not keep his higher ranked opponent at bay for much longer.
Del Potro earned a pivotal break and a 3-2 lead after Kohlschreiber dumped a forehand in the net. Victory was in sight for the popular 29-year-old, however he encountered turbulence as he tried to pull away on the scoreboard.
The German created four break-points in the following game, yet was unable to force a breakthrough. He tried desperately to hit back, but there was to be no last-gasp heroics.