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Bartunkova looked set to cause a massive shock, but Sabalenka fought back to claim a 2-6 7-6 (7-2) 6-4 victory in two hours and 25 minutes.

The Czech came out on the offensive from the very start and reeled off five straight games, with Sabalenka unable to find any answers to her big-serving opponent.

The world No.1 did fend off four set points in her next service game to delay the inevitable, but then failed to convert two break points as Bartunkova took the first set.

Bartunkova's dominance continued at the start of the second as she raced into a 4-0 lead, but Sabalenka soon put together a response, winning each of the next five games.

In the tie-break, Sabalenka turned up the heat even more; from 2-1 down, she did not give Bartunkova another sniff, as she won six straight points to force a decider.

The pair traded breaks in the final set, with Bartunkova even taking a 4-3 lead, but Sabalenka dropped just five more points after that as she took the win on her third match point.

Sabalenka dug in deep, saving 11 of the 17 break points she faced, but she will have to make a swift improvement as she will face Jessica Pegula in the final four.

She has only ever made it through to two grass-court finals, losing them both, but neither of those came in Berlin, and the Belarusian will hope she can use this result as a springboard.