Alhaji Kamara and Abdul Sesay netted for Sierra Leone as they overcame Chad 2-1, and the tie ended 2-2 on aggregate.
However, Leger Djimranger's away goal ensured that Chad emerged winners on the away goal-rule on Tuesday afternoon.
The 2018 FIFA World Cup qualification (CAF) first round second-leg was played at the Adokiye Amiesimaka Stadium in the Nigerian city of Port Harcourt due to the Ebola outbreak in Sierra Leone.
Chad went into the crucial encounter leading 1-0 aggregate thanks to Leger Djimranger's second-half strike at the Stade Nacional in N'Djamena.
The home side began the game brightly as they looked to grab an early goal. However, Les Sao stood firm at the back.
Chad increased their tempo towards half-time, and they hit the back of the net through their defender Leger Djimranger, having already netted in the first-leg against the same opposition.
This time Djimranger beat Sierra Leone goalkeeper Solomon Morris with a glancing header in first-half stoppage time. Les Sao were leading 1-0 during the half-time break.
Sierra Leone restored parity on the day in the 70th minute though Alhaji Kamara. However, the Leone Stars were now trailing 2-1 on aggregate.
Abdul Sesay made it 2-1 to Sierra Leone after chest trapping the ball, and volleyed it home in the 83rd minute. It was now 2-2 on aggregate.
Nevertheless, Chad managed to hold on in the remaining minutes, and Sierra Leone won 2-1 on the day.
The two nations drew 2-2 aggregate, but Chad emerged victorious on the away goal-rule.
Chad will now take on African football giants Egypt in the World Cup qualification second round in November, 2015.
Sierra Leone XI: Morris, Dumbuya, Kamara, Bangura, Quee, Sesay, Kamanor, Dunia, Bangura, Kanu, Kamara.
Chad XI: Gerrard, Djimranger, Abaya, Djikoloum, Nicaise, Haroun, Mahamat, Mbaiam, Ndouasel, Madtoingue, Douma.