Argentina striker Tevez, who left United for City at the end of last season, scored both goals as his club edged the first leg 2-1 at Eastlands but his "shut it" celebration aimed at Neville followed by a one-fingered gesture from the United man sparked a war of words.
Tevez labelled stalwart Neville a "bootlicker" and a "moron" during an interview on Argentine radio for backing United boss Alex Ferguson decision's not to pay out the money to keep hold of him last summer.
City chief executive Garry Cook's claim that City will be the biggest club in the world would have also touched a nerve down the road where United's dominance of their own town, let alone the country is suddenly under threat.
Ferguson later claimed that Tevez should have been sent off for a foul on Wes Brown.
Police made several arrests before and during the first leg last week and extra officers are on duty for the return at Old Trafford when holders United will be desperate to overturn the narrow deficit and set up a Wembley final with Aston Villa.
It is the perfect moment for United to puncture the optimism flowing through City who are tantalisingly close to their first meaningful silverware since 1976 just weeks into the reign of Roberto Mancini.
United winger Nani said Saturday's 4-0 victory over Hull City to put United back on top of the Premier League had been a huge boost going into the return with City, particularly with striker Wayne Rooney appearing unstoppable.
"I'm sure it'll be a fantastic atmosphere against City and I'd love to be involved. Hopefully we can get the win," the Portuguese told United's website on Monday.
"Everyone is very happy. It's great to be top of the table and it's given everyone a lot of confidence. We're playing well, scoring goals and feeling good."
Rooney's red-hot form will be a major concern to City and Mancini after the England man scored all four goals against Hull but United, who have Rio Ferdinand back in defence, will also be wary of the tireless Tevez.
The swarthy Argentine was the darling of the Stretford End during a two-year spell at United in which he scored 19 goals in 63 goals but his goal celebration and comments about Neville could mean he gets a less than warm welcome back.
