Mbonambi – who will earn his 60th Test cap this weekend – takes over the captain’s responsibilities in the absence of regular captain, Siya Kolisi, who is making encouraging progress following surgery to his knee, and stand-in captains Eben Etzebeth and Duane Vermeulen, who remained behind in South Africa with a group of players in a conditioning camp.
Steenekamp, who has progressed through the South African rugby ranks in the past few seasons after representing the Junior Springboks and making a strong statement for the Vodacom Bulls in the Vodacom United Rugby Championship, is the only uncapped player in the squad, and will become Springbok No 933.
Springbok coach Jacques Nienaber named a vastly different matchday squad to the side that defeated Argentina 22-21 at Emirates Airline Park last week, with the only two players retaining their places in the starting team being flyhalf Manie Libbok and lock Marvin Orie.
Nienaber also named a rejigged bench, with utility forward Jean-Luc du Preez and scrumhalf Herschel Jantjies donning the jersey for the first time this season as the coaches attempt to give as many players as possible a chance to prove themselves before naming their 33-man Rugby World Cup squad on Tuesday, 8 August.
Gerhard Steenekamp is in line to make his Springbok debut on Saturday.
Mbonambi will form a strong front row with props Trevor Nyakane and Thomas du Toit, while Jean Kleyn will earn his second start in a lock combination with Orie.
Nienaber also named a physical loose trio with flankers Deon Fourie and Franco Mostert, and No 8 Jasper Wiese, while experienced scrumhalf Cobus Reinach will join forces with Libbok at halfback.
The backline also features grunt and class as Makazole Mapimpi, Canan Moodie (both wings) and Damian Willemse (fullback) form an exciting back three, while Andre Esterhuizen and Lukhanyo Am – who has been named vice-captain for the match – will pair up in the midfield.
Wing Kurt-Lee Arendse has been declared fit to play after suffering a finger injury on Saturday and will provide backline cover with Jesse Kriel and Jantjies on a bench featuring a five-three split in favour of the forwards.
“This selection includes plenty of Rugby World Cup and Castle Lager Lions Series winners as well as a former Irish international in Jean Kleyn, and this just shows the quality of the depth we have,” said Nienaber.
Lukhanyo Am is the Boks' vice-captain this weekend.
“We’ve been emphasising the importance of giving as many players as possible a fair chance to show what they can do with an eye on finalising our Rugby World Cup squad, so we are pleased to give Herschel and Jean-Luc an opportunity to play.
“This is going to be a massive physical battle and there will be a lot of pressure on the players mentally and physically, which is exactly the type of situation we would like to see them in as we enter our World Cup warm-up games.”
Nienaber admitted that while this may be a vastly different team to last week, most of the players had extended experience of the Springbok environment and knew the importance of taking the opportunity to impress.
“There’s a fair bit of experience within this squad, and apart from Gerhard, most of the players have been in the selection mix in the last two seasons,” said Nienaber.
“There is not a player in our enlarged squad who is fully confident that he will be in the World Cup squad, so the competition for places is intense. Each one of the players is desperate for an opportunity to play and it’s evident in the way they’ve been training and in the hard work they’ve been doing off the field, so we’re excited to see what they bring this weekend.”
Marvin Orie and Jean Kleyn will start as lock combination for a second time this season.
Nienaber was pleased with the speed at which the players acclimatised to the time zone in Argentina and said they were preparing for another hard grind at Velez Sarsfield.
“Argentina have shown in the last two seasons that they are a force to be reckoned with and they are particularly tough to beat at home,” said Nienaber.
“They pride themselves on their physicality and set pieces and they have an unbelievable fighting spirit, so we are anticipating another feisty battle against them.”
Nienaber said SA Rugby Director of Rugby Rassie Erasmus would join the squad in Argentina on Thursday after working with the group of players who remained in South Africa in the last few days.
Springbok team to face Argentina in Buenos Aires:
15 – Damian Willemse (DHL Stormers) – 30 caps, 36 pts (2t, 4c, 4p, 2d)
14 – Canan Moodie (Vodacom Bulls) – 5 caps, 5 pts (1t)
13 – Lukhanyo Am (Cell C Sharks) – 34 caps, 30 pts (6t)
12 – Andre Esterhuizen (Harlequins) – 12 caps, 0 pts
11 – Makazole Mapimpi (Cell C Sharks) – 37 caps, 110 pts (22t)
10 – Manie Libbok (DHL Stormers) – 6 caps, 31 pts (1t, 10c, 2p)
9 – Cobus Reinach (Montpellier) – 25 caps, 45 pts (9t)
8 – Jasper Wiese (Leicester Tigers) – 21 caps, 5 pts (1t)
7 – Franco Mostert (Honda Heat) – 64 caps, 15 pts (3t)
6 – Deon Fourie (DHL Stormers) – 6 caps, 0 pts
5 – Marvin Orie (DHL Stormers) – 13 caps, 0 pts
4 – Jean Kleyn (Munster) – 1 cap, 0 points (Ireland 5 caps)
3 – Thomas du Toit (Cell C Sharks) – 17 caps, 0 pts
2 – Bongi Mbonambi (captain, Cell C Sharks) – 59 caps, 60 pts (12t)
1 – Trevor Nyakane (Cell C Sharks) – 59 caps, 5 pts (1t)
Replacements:
16 – Joseph Dweba (DHL Stormers) – 5 caps, 0 pts
17 – Gerhard Steenekamp (Vodacom Bulls) – uncapped
18 – Vincent Koch (Cell C Sharks) – 44 caps, 0 pts
19 – Jean-Luc du Preez (Sale Sharks) – 13 caps, 10 pts (2t)
20 – Evan Roos (DHL Stormers) – 4 caps, 0 pts
21 – Herschel Jantjies (DHL Stormers) – 23 caps, 25 pts (5t)
22 – Jesse Kriel (Canon Eagles) – 60 caps, 60 pts (12t)
23 – Kurt-Lee Arendse (Vodacom Bulls) – 9 caps, 50 pts (10t)
Springbok record against Argentina
Played 35; Won 31; Lost 3; Drawn 1; Points for: 1215, Points against: 678; Tries scored 143, Tries conceded 64; Highest score 73-13; Biggest win 60 points. Win % 89%.
