Andy Murray crashed out of the Brisbane International with a second-round defeat to an inspired Daniil Medvedev on Wednesday.

Murray made a winning comeback against James Duckworth on New Year's Day, but was soundly beaten 7-5 6-2 in his first meeting with 22-year-old Medvedev.

Three-time grand slam champion Murray said he is unsure how long he will carry on playing at the highest level after beating Duckworth, having missed so much of last season following hip surgery 12 months ago.

The Brit was no match for impressive fourth seed Medvedev, who blasted down 16 aces and broke twice in each set on Pat Rafter Arena to book a quarter-final encounter with Milos Raonic.

Murray was a break down at 2-1 after looping a backhand way beyond the baseline and continued to look out of sorts before getting back on serve at 4-4.

Medvedev was far more aggressive and served out the opening set to love after breaking again for a 6-5 lead with a searing forehand winner.

The Russian was relentless and opened up a 4-0 lead in the second set, with a rusty Murray racking up the unforced errors.

Medvedev returned with vigour and did not face a solitary break point in a one-sided second set, which he ended with an ace to send Murray packing soon after Rafael Nadal withdrew from the tournament due to a thigh injury.