Andy Murray moved on from the first round after winning two straight sets against Norwegian qualifier Viktor Durasovic on Tuesday.
On Wednesday, much tougher opposition awaited in the form of Italian world champion Jannik Sinner, who is first seeded in the tournament.
Sinner has won four ATP titles this year and is seen as one of the big future names in men's tennis.
But in the first set, Murray showed that old is the oldest.
The 14-year-old Murray pressed the favorite Sinner and took the first set to tiebreak.
Murray had the lead with 5-4 in the tiebreak when Sinner was to serve.
Then the 20-year-old made a double error and Murray was able to take home the subsequent set ball.
In the second set, Sinner won the first game, but Murray connected the grip by winning three straight.
Murray continued to impress and took the lead 5-3.
And with one game left to win, the veteran made no mistake.
Murray broke Sinners serve and won the match 7-6 (7-4), 6-3.
In the quarterfinals, the American Tommy Paul is waiting, who earlier in the tournament beat Leo Borg.
Next to the quarterfinals is also reigning champion Denis Shapovalov who defeated the Italian Andrea Vavassori.
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Andy Murray is further in the Stockholm Open.
Photo: TT