Tigers back-rower Croft is among five members of the starting XV making their Lions debuts as he lines up in the No6 shirt, and Ellis is among a further six debutants named among the replacements.
Brian O’Driscoll will captain the team in Johannesburg.
Head coach Ian McGeechan said: "The starting XV is very different to the one that played against the Royal XV on Saturday. There are only three players backing up from that match, but six of the replacements have been promoted to Wednesday's starting XV. This is in line with our intention that all players will play a full match in the first three matches on tour.
"The team has trained well. We have worked on several key areas following the first match which has given us a base from which to keep developing our game.”
Every match of the Lions tour will be shown live in the ABC Bar at Leicester Tigers’ Welford Road stadium.
British & Irish Lions Team (v Golden Lions, Wednesday 6.10pm)
15 Rob Kearney (Leinster/Ireland)
14 Tommy Bowe (Ospreys/Ireland)
13 Brian O'Driscoll (Leinster/Ireland)
12 Jamie Roberts (Cardiff Blues/Wales)
11 Ugo Monye (Harlequins/England)
10 Stephen Jones (Scarlets/Wales)
9 Mike Phillips (Ospreys/Wales)
1 Gethin Jenkins (Cardiff Blues/Wales)
2 Lee Mears (Bath/England)
3 Phil Vickery (London Wasps/England)
4 Nathan Hines (Perpignan/Scotland)
5 Alun-Wyn Jones (Ospreys/Wales)
6 Tom Croft (Leicester Tigers/England)
7 David Wallace (Munster/Ireland)
8 Jamie Heaslip (Leinster/Ireland)
Replacements
16 Ross Ford (Edinburgh/Scotland)
17 Euan Murray (Northampton Saints/Scotland)
18 Stephen Ferris (Ulster/Ireland)
19 Andy Powell (Cardiff Blues/Wales)
20 Harry Ellis (Leicester Tigers/England)
21 James Hook (Ospreys/Wales)
22 Shane Williams (Ospreys/Wales)
