The Lions will be without star playmaker Elton Jantjies when they face the Bulls at Loftus Versfeld on Saturday.
The 25-year-old pivot dislocated his finger in last week's 52-24 victory over the Jaguares in Johannesburg.
But he will be replaced by Marnitz Boshoff, who has been playing in the domestic Currie Cup competition all season long.
Head coach Johan Ackermann believes that, despite not having played a single Super Rugby game this season, Boshoff knows what is expected of him and backs him to handle the pressure of this important tussle.
"His inclusion will probably raise a few eyebrows, especially because it’s an important match, but we have full confidence in Marnitz," Ackermann told Netwerk24.
"We don’t expect Marnitz to come up with the same magic as Elton.
"We just want him to stamp his own authority on the match. He is a former Springbok who knows the pressure of finals. We couldn’t opt for a better player to replace Elton."
A win for either side will consolidate their place at the summit of the Africa One and Two Conference tables, which adds even more pressure to this South African derby.
The visitors are currently two points ahead of the Sharks in the Africa Two Conference while the three-time champions are equal, on points, with the Stormers, but a better points difference sees them lead the Africa One Conference table.