After reportedly already having sealed a deal for Porto star Otamendi, Chelsea appear to have more work to do to fight off rivals for his signature.
Jose Mourinho was reported to have beaten the likes of Barcelona and AC Milan earlier this month to land the defender and was set to sanction a swoop this January if positive talks could be resolved.
However, Portuguese newspaper A Bola are now saying that Zenit St Petersburg are determined to land their man and have him "in their crosshairs".
Chelsea already have a number of defenders in the squad, but the futures of David Luiz and Cesar Azpilicueta have been question ever since the former Real Madrid manager took over in the summer.
Mourinho's opposite number at Zenit, Luciano Spalletti, is also a highly respected coach aorund Europe and the Russian Premier League club could offer Otamendi and combination of playing time and more than decent salary to lure him away from Chelsea.
A Bola say reports in Russia believe an offer in the region of €20million is on the table from Zenit for the centre-back.