(Bloomberg) -- Goldman Sachs Group Inc. has switched sides to advise Aviva Plc on its £3.3 billion ($4.2 billion) takeover bid for Direct Line Insurance Group Plc, only eight months after helping the target successfully defend against another suitor.

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The New York-based investment bank — with a team led by bankers Anthony Gutman, Nimesh Khiroya and Bertie Whitehead — is advising London-listed Aviva on its bid alongside Citigroup Inc., according to a regulatory statement. Direct Line, known for its motor insurance offerings in the UK, has rejected the offer as “highly opportunistic” and declined to engage further.

Goldman was among the cohort of advisers when Direct Line rebuffed a proposal from Belgian rival Ageas in March that valued it at around £3.2 billion. The Goldman team fronted by Mark Sorrell helped fend off Ageas with Direct Line’s fellow advisers at Morgan Stanley, RBC Capital Markets, Robey Warshaw and JPMorgan Cazenove.

Valeriya Vitkova, a senior lecturer at City University of London’s Bayes Business School, noted that Goldman would be using a “clean team” on the deal, meaning a totally separate group of personnel from the previous engagement with Direct Line.

“However, there is still increased scope for employees from the same organization to talk to each other and this will be difficult to prevent,” Vitkova said. “In terms of reputational damage, it is likely that there is going to be some negative impact as well.”

After Ageas walked away, Goldman and Direct Line mutually agreed to end the engagement in the summer and the US bank has had no active investment banking roles since then, the lender said Thursday in response to Bloomberg News queries.

Goldman has been a corporate broker for Aviva since last year. In the latest defense against Aviva, Direct Line retained Morgan Stanley, Robey Warshaw and RBC Capital Markets.

“Having played a key role in a contentious defense process last time, GS should know exactly where the killing zone is (or at least was) in March for shareholders,” merger arbitrage specialist MKP Advisors wrote in a note Thursday.

Corporate brokers in the UK advise clients and support their investor relationships for minimal fees in the expectation of winning more lucrative mandates on bigger deals, such as mergers or equity sales. Firms typically call their brokers to weigh in or provide defense when they receive a takeover approach. However, this unique UK broker and adviser situation can lead to tough choices for the banks when M&A kicks off.