Just as global markets nurse a hangover from their Q1 binge on cheap ECB lending — a circa 1 trillion euro flood of 1%, 3-year loans to euro zone banks in December and February (anodynely dubbed a Long-Term Refinancing Operation) — there’s every chance they may get, or at least need, a proverbial hair of the dog.

At least that’s what Citi chief economist Willem Buiter and team think despite regular insistence from ECB top brass that the recent two-legged LTRO was likely a one off.

Even though Citi late Wednesday nudged up its world growth forecast for a third month running, in keeping with Tuesday’s IMF’s upgrade , it remains significantly more bearish on headline numbers and sees PPP-weighted global growth this  year and next at 3.1% and 3.5% compared with the Fund’s call of 3.5% and 4.1%.

But its euro zone calls are gloomiest of all. First off, it sees two consecutive years of economic contraction of the bloc as a whole — a 1.0% shrinkage this year followed by 0.2% drop in 2013. Against this dire backdrop, it expects  Spain to be forced to seek Troika (EU, IMF and ECB) support later this year that will be focussed on recapitalizing and restructuring its ailing banks and it also expects both Portugal and Ireland to need second bailouts from the same source.

And with that sort of pressure from deleveraging, austerity, sovereign debt stress and recession , the ECB will have to bring out yet another punchbowl, it reckons.