The Lions beat Benin 1-0 courtesy of Idrissa Gueye's 69th-minute strike to reach the last four, keeping a clean sheet for the fourth time at this year's competition.
Only Algeria has managed to breach Senegal's steely defence so far, but on Monday (AEST) it goes up against a Tunisia side that eased to a 3-0 quarter-final victory over Madagascar.
Senegal coach Aliou Cisse expects another tough challenge.
"Tunisia are a good team who do good things. We won't underestimate anyone and we won't lack concentration," he said.
"There are still two matches to go. We came here with ambition, we hoped to reach the quarter-final, but we'll keep our feet on the ground.
"We haven't reached this stage since 2006. It's been 13 years and Senegal haven't been here, so this already represents a progression.
"We'll have more humility. I believe these are great professionals. I've always been confident in the work we're doing."
Tunisia put in an impressive second-half display against Madagascar, scoring twice in eight minutes before Naim Sliti added a third in second-half stoppage-time.
"We are the first to beat Madagascar," Tunisia boss Alain Giresse said. "This proves the quality of this team in this competition.
"We are very satisfied we are in the semi-finals. Now we are at this stage of the competition, which Tunisia had been waiting for for many years. It was an objective.
"We have to play this semi-final with all our weapons and obviously try to go as far as possible. We know what to do about it. We know what to expect.
"We want to finish this competition in style."
PLAYERS TO WATCH
Senegal - Alfred Gomis
SPAL goalkeeper Gomis has conceded just once at this year's tournament but his toughest test awaits against Tunisia.
Tunisia - Youssef Msakni
Msakni was instrumental in turning the quarter-final against Madagascar in his team’s favour, providing the assist for Ferjani Sassi's opener before netting the second himself.
KEY OPTA FACTS
- It will be the sixth encounter between Senegal and Tunisia in the Africa Cup of Nations, but the first in semi-finals.
- Senegal has won its past three games in the Africa Cup of Nations, its longest streak in the competition.
- Tunisia will play its sixth Africa Cup of Nations semi-final. The Carthage Eagles have qualified for the final twice previously, against Zambia in 1996 and against Nigeria in 2004.
- Senegal has kept a clean sheet in seven of its past nine games in the Africa Cup of Nations (3 goals conceded overall), after failing to do so in each of their previous 14.
- Tunisia's striker Wahbi Khazri has been involved in 29 shots in the 2019 edition (16 shots attempted, 13 chances created), more than any other player.