Aberdeen boss Mark McGhee has revealed his out-of-contract players are close to proving they deserve new deals with the Dons, reports the Scottish Sun.
The quartet can sign pre-contracts in January but Aberdeen boss McGhee refused to rush into talks about keeping them.
Instead he demanded they prove themselves worthy of an offer from the cash-strapped club.
He said: "The lads whose contracts are coming up for renewal have responded in the manner I had hoped.
"They have risen to the challenge put in front of them and that is exactly what we needed.
"Mark Kerr has been doing very well and I was very pleased with Gary McDonald's display against St Johnstone. Richard Foster has also been terrific in recent weeks. Lee Miller also came up with his best game yet last Saturday so I couldn't be happier with this group."
The problem now for McGhee is to persuade the Aberdeen board of directors to find the funds to keep their top talent.