Germany international Rudiger has been left out of the Blues’ matchday squad for their last two games amid rumours he is seeking a move away from Stamford Bridge.
With the arrival of Silva from Paris Saint-Germain, the 27-year-old has fallen down the pecking order of centre-backs at the west London club.
Merson suggests Lampard should change his system from a back four to a back three to bring Rudiger back into the fold, and to also ensure 36-year-old Thiago Silva isn’t exposed.
‘Chelsea have got five centre-backs and that’s too many unless you’re playing three every week – and I think that’s what Lampard should do.
‘At the moment he’s playing a back four and someone is always going to miss out. Right now it’s Rudiger, which surprises me.
‘I thought Kurt Zouma or Andreas Christensen would go this summer because Rudiger is better than both of them.
‘But if Lampard switches to three at the back with wing-backs, he solves the problem and gets the best out of Thiago Silva, who won’t be so exposed in that system.
‘I’ve always been a big fan of Thiago Silva and signing him on a free was a no brainer. But at PSG he only had to exert himself four or five times a season.
‘In the Premier League, it’s relentless. He needs to play in the centre of a three for me. And playing that way means Rudiger stays.’