By Yoruk Bahceli and Stefano Rebaudo

(Reuters) - The European Central Bank looks set to deliver another interest rate cut on Thursday it had little appetite to point to just weeks ago.

Data signal a euro zone economy in worse shape than when policymakers last met, boosting bets on speedier rate cuts than the quarterly pace June and September cuts suggested.

"If the ECB does not cut in October, the market will think that the central bank is behind the curve and potentially making a policy error," said Deutsche Bank chief European economist Mark Wall.

Here are five key questions for markets:

1/ Will the ECB cut rates this week?

All but certainly. Traders are banking on around a 90% chance of a 25 basis-point cut, a huge increase from as low as 20% when the ECB met last month.

Euro zone business activity that unexpectedly contracted in September led to a surge in October bets, as investors feared that the ECB, so far sticking to its data-dependency mantra, may not cut rates quickly enough.

Several policymakers have already made the case for an October cut. Even ECB chief Christine Lagarde has hinted at one, saying confidence in falling inflation would be reflected in the bank's decision.

2/ Is this the start of back-to-back rate cuts?

Yes, Wall Street economists reckon.

And traders are pricing in just over three cuts at the four meetings following October.

ECB policymakers, however, are not quite there yet. Centrist Finnish governor Olli Rehn has repeated the message that the pace and scale of further cuts will be decided meeting by meeting.