Leicester duo Jonny Evans and Caglar Soyuncu are among a number of centre-back options being considered by Manchester City, Sky Sports News understands.
The pair have been superb for the Foxes during an impressive start to the season under Brendan Rodgers that has put them second in the Premier League table after 12 games.
City are fourth - a point behind Leicester and nine behind league-leaders Liverpool - after having injury problems at centre-back and failing to sign a replacement for Vincent Kompany in the summer.
Boss Pep Guardiola wanted Harry Maguire from Leicester, but joined Manchester United - and now City are monitoring those who have stepped up in the England defender's absence at the King Power.
However, Guardiola has previously insisted the club will not buy a new centre-half in the January transfer window, despite having to play midfielder Fernandinho in place of the injured Aymeric Laporte.
City wanted to sign Evans from West Brom in 2017 but had a number of bids rejected before he eventually signed for Leicester a year later for just £3.5m, after Guardiola's side bought Laporte in January 2018.
The Northern Ireland international has made 42 appearances for the Foxes since and started all 12 of Leicester's Premier League games this season alongside Soyuncu.
When does the January transfer window open?
As the January transfer window inches ever closer, clubs across the Premier League, Europe and beyond will be identifying potential transfer targets and holding discussions with clubs and agents over future deals.
At this traditionally difficult time to make big moves, the start of the new year looks set to be frantic for a host of top Premier League clubs.
Where can you follow all the latest transfer news?
As well as keeping an eye on Sky Sports News, you can make sure you don't miss a thing with our dedicated Transfer Centre blog.
There will also be the return of the Transfer Talk Podcast and some exciting new features coming your way...