The heavy defeat at Celtic Park should serve as a wake-up call for everyone at Hearts.

There has been progress under Wouter Vrancken, but the Belgian has made it clear his side remain some way short of where he wants them to be.

Sunday's result was a stark reminder of that reality.

There were positives to take from the underlying statistics, but numbers can be misleading. Hearts cannot afford to present the champions with the kind of opportunities they did in Glasgow and expect to escape punishment.

Mistake after mistake was ruthlessly exploited. Those errors must be addressed quickly, because another demanding test awaits.

Trabzonspor have invested heavily in their squad, spending £60m on new recruits over the summer, and have started the campaign in impressive goalscoring form.

Thomas Reis' side have netted 18 goals in their past six matches, conceding just three. Hearts will need to be far more disciplined and defensively resilient if they are to leave Turkey with a result.

When the Conference League fixtures were announced, this trip was immediately identified as arguably the toughest of Hearts' six league-phase assignments. Anything they bring home would be a welcome bonus.

But the European challenge is only part of the story.

After returning from Turkey, Hearts must switch their attention to two difficult Premiership fixtures, with a trip to Fir Park followed by former boss Derek McInnes' return to Tynecastle with Rangers.

The Celtic Park defeat was a painful reminder of how far Hearts still have to go. The response over the next week will tell us much more about the direction in which they are heading.