The Scotland wing bagged three tries against the same opponents in Johannesburg on Wednesday as the tourists won 54-7.
The sides will meet again this weekend in Pretoria after the Lions’ original opponents, the Bulls, withdrew due to a Covid outbreak in their squad.
Van der Merwe is one of four Scotland internationals in the starting XV for the match at Loftus Versfeld, centre Chris Harris, prop Rory Sutherland and flanker Hamish Watson being the others.
Finn Russell, the Scotland stand-off, is named among the replacements, one of only two backs on the bench. The other is tour captain and scrum-half Conor Murray.
Jamie George of Saracens will captain the side against Sharks and there are 13 changes to the team in total with only Elliot Daly and van der Merwe retained.
The Lions were hit by two Covid positive cases earlier this week but earlier on Friday the tour PCR screening programme returned a negative set of results.
A statement from the Lions said: “On Wednesday 7 July, one member of staff tested positive for COVID-19. As a result, the individual and four close contacts (one player and three members of staff) are being isolated at the team hotel.”
Warren Gatland, the Lions head coach, said: “It’s obviously been a slightly turbulent week, but we remain determined to keep rolling with the punches.
“In many ways, the challenges we’ve faced this week have strengthened our resolve to do everything we can to overcome the challenges created by Covid.
“The feeling in the camp on Wednesday night was just to give it a crack – I was really proud by how everyone reacted, particularly the match day squad who would have never prepared for a game like that before.”
British and Irish Lions (v Sharks, Saturday, Loftus Versfeld, Pretoria, 5pm BST)
15. Liam Williams (Scarlets, Wales)
14. Anthony Watson (Bath Rugby, England)
13. Elliot Daly (Saracens, England)
12. Chris Harris (Gloucester Rugby, Scotland)
11. Duhan van der Merwe (Worcester Warriors, Scotland)
10. Dan Biggar (Northampton Saints, Wales)
9. Gareth Davies (Scarlets, Wales)
1. Rory Sutherland (Worcester Warriors, Scotland)
2. Jamie George – captain (Saracens, England)
3. Tadhg Furlong (Leinster Rugby, Ireland)
4. Maro Itoje (Saracens, England)
5. Jonny Hill (Exeter Chiefs, England)
6. Tadhg Beirne (Munster Rugby, Ireland)
7. Hamish Watson (Edinburgh Rugby, Scotland)
8. Jack Conan (Leinster Rugby, Ireland)
16. Ken Owens (Scarlets, Wales)
17. Wyn Jones (Scarlets, Wales)
18. Kyle Sinckler (Bristol Bears, England)
19. Courtney Lawes (Northampton Saints, England)
20. Sam Simmonds (Exeter Chiefs, England)
21. Tom Curry (Sale Sharks, England)
22. Conor Murray (Munster Rugby, Ireland)
23. Finn Russell (Racing 92, Scotland)
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