The Liberal Democrats retained control in Eastbourne but saw their majority cut to just one seat as the Tories capitalised on this year's huge council tax rise.
Having lost a seat in Old Town to Tory challenger Ian Lucas, the balance of power is now on a knife edge.
Before last night, the party held 15 seats and the Tories 12. But with a Tory gain and a Lib Dem loss, the make-up is now 14 to 13 in favour of the Lib Dems.
Tories had played on residents' anger in Eastbourne at being hit with a 38 per cent council tax rise, the fourth highest in England.
The Tories had considered Eastbourne a top target after they were ousted from their stronghold last year in a shock Lib Dem win.
Thirty-three candidates from five parties contested nine seats in nine wards.
The Tory gain last night came in Old Town, a ward previously at the centre of anti-Conservative feeling after their County Hall colleagues sanctioned the closure of Old Town Library.
However, Coun Lucas said the council tax rise plus the demand for fresh blood in Old Town helped depose John Creaven.
He said: "The council tax rise certainly didn't help the Lib Dems but it wasn't the deciding factor. We worked very hard all year round to convince people of our policies."
Mayor Olive Woodall retained her seat in Hampden Park, as did her deputy Norman Marsh in St Anthony's.
Lib Dem Alan Carroll failed to snatch the Sovereign seat from Tory Patrick Warner.
Lib Dem leader Beryl Healy said: "We knew that with a 38 per cent council tax increase we were fighting to stay in but despite that we still retained the council."
Tory opposition leader Graham Marsden paid tribute to newly-elected Coun Lucas, saying he will be a strong worker in Old Town.
He added: "The Liberal Democrats may just be in control but they are hanging on by their fingertips."
Turnout was 33.6 per cent, down slightly on last year's 33.9 per cent.
RESULTS (* denotes sitting councillor)
DEVONSHIRE: Elected: Neil Stanley* (LD) 1,222. Not elected: Kenneth Graham (C) 723, Nancy Dalton (G) 160 HAMPDEN PARK: Elected: Olive Woodall* (LD) 955. Not elected: David Brinson (L& Coop) 439, Edward Abella (C) 414, Leslie Dalton (G) 107.
LANGNEY: Elected: Robert Slater* (LD) 828. Not elected: Thomas Walters (C) 722, Jonathan Pettigrew (L) 153, Christine Quarrington (G) 62.
MEADS: Elected: David Elkin* (C) 2,202. Not elected: Steven Wallis (LD) 518, David Buck (L) 216, Clive Gross (G) 154.
OLD TOWN: Elected: Ian Lucas (C) 1,812. Not elected: John Creaven* (LD) 1,471, Liam Stephens (G) 173, Robert Rossetter (L) 152.
RATTON: Elected: Sandie Howlett* (C) 1,803. Not elected: Peter Durrant (LD) 652, Martin Falkner (L) 205, Kevin Moore (G) 123.
ST ANTHONY'S: Elected: Norman Marsh* (LD) 1,349. Not elected: Sheila Charlton (C) 810, Nora Ring (L) 190, Kenneth Alderton (UKIP) 138.
SOVEREIGN: Elected Patrick Warner* (C) 1,255. Not elected: Alan Carroll (LD) 1,040.
UPPERTON: Elected: Ann Murray* (C) 1,418. Not elected: Stafford Gowland (LD) 845, Peter Tucker (L) 153, John Morrison (G) 144.
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