However, both deals collapsed as Rudiger, who was reluctant to play for another club in London, stayed despite a late offer from Roma.
Chelsea delayed allowing Tomori to leave and the player opted to stay and fight for his place amid a late loan bid from West Ham.
In fact, both Rudiger and Tomori were hopeful of winning over Lampard and forcing their way into the first-team picture but Kurt Zouma and summer signing Thiago Silva have formed an impressive partnership at the back, starting four of the last five Premier League games together, conceding just one goal.
Rudiger played in Wednesday's 4-0 Champions League win at Sevilla but that was only his third outing of the season while Tomori has not featured in any competition since Sept. 29.
Tomori was one of Chelsea's breakthrough stars in the 2019-20 campaign and last December he signed a contract tying him to the club until 2024. Lampard is keen to retain the 22-year-old on a long-term basis but recognises the need for regular minutes to aid his development.
Lampard has publicly highlighted the need for rotation with Chelsea due to play eight games this month but Rudiger and Tomori are still unlikely to receive sufficient minutes to suggest they will play important roles in the second half of the season.
Barcelona have been linked with a move for Rudiger but they are yet to make any formal contact over a possible transfer. Everton have since signed Ben Godfrey but West Ham may revive their interest in Tomori.
It is unclear whether Chelsea would allow both players to leave -- and any injuries over the next few weeks will come into their thinking -- but intermediaries have been made aware of the potential for Rudiger and Tomori to play elsewhere.