West Bromwich Albion are chasing Aston Villa midfielder Sidwell after taking Nicky Shorey from their neighbours last week.
The former Chelsea star was lined up for a £2m switch to Fulham earlier this summer.
But the deal was aborted when boss Roy Hodgson quit for Liverpool.
Villa are still willing to cash in on Sidwell, 27, to get his £48,000-a-week salary off their wage bill.
But Villa are reluctant to sell another star to their Midland rivals and Sidwell would prefer to run his contract down as he will be a Bosman next summer.