The World Cup winning captain named Sheridan and Ospreys and Wales wing Shane Williams as his two certainties for the Lions tour party this week, with Wales' Grand Slam skipper Ryan Jones as another odds-on choice.
If Sheridan does make a second Lions tour then he could find himself going head-to-head with Smit in the front row.
The South African played at tight head prop during the Springboks' recent tour of the UK, including and 42-6 record defeat of England at Twickenham, and is ready to play there again or in his more customary position of hooker.
Sheridan played five games on the 2005 Lions tour to New Zealand, but had to play second fiddle to Wales' Gethin Jenkins when it came to Test selection at loose head. The two rivals were on opposing sides in last weeks Wales v England Six nations match at the Millennium Stadium, with Jenkins ending on the winning side.
Having watched the first two rounds of the RBS Six Nations, Smit claimed that few players as yet had booked their tickets to South Africa this summer.
"They're all trying to impress the Lions selectors, but it's going to be hard for McGeechan," said Smit.
"The guys who I think will definitely be coming over are Andrew Sheridan and Shane Williams, and possibly Ryan Jones. But they'll be battling for places over the next few weeks."
Smit's return to the No 3 jersey last year - he played in that position for South Africa Under 21 and for the Sharks against the 1997 Lions as a replacement - was in response to a request from coach Peter de Villiers, who wanted to use his experience as a captain but to also include Bismarck du Plessis at hooker.
Smit made an early return to South African rugby last summer after a brief sojourn at ASM Clermont Ferrand and re-signed for the Sharks. That meant joining du Plessis as a front row option for the top South African Super 14 team.
In last weekend's opening Super 14 clash with the Stormers, Smit started at hooker in a front row that saw Deon Carstens and Jannie du Plessis as props. After their 20-15 away win, which featured a try from Smit, there is no change for Saturday's home game against the Lions with Bismarck du Plessis once again starting on the bench.