Leicester forward Kelechi Iheanacho struck in the first half to give Nigeria a deserved 1-0 win over Egypt in their Africa Cup of Nations Group D opener in Garoua.
Iheanacho fired the Super Eagles ahead when he drilled a half-volley into the top corner after 30 minutes.
Nigeria were close to doubling their lead early in the second half as Taiwo Awoniyi saw his close-range header pushed onto the crossbar by Egypt goalkeeper Mohamed El Shenawy, who also later saved from substitute Chidera Ejuke.
Egypt never really got out of first gear and failed to carve out many clear openings for Liverpool forward Mohamed Salah, who was put through during the closing stages – but the Pharaohs captain could not find a telling finish.
Sudan goalkeeper Ali Abou Achrine saved a late penalty to ensure they secured a 0-0 draw with Guinea Bissau in Garoua on Tuesday in an inauspicious start for both at the Africa Cup of Nations finals.
Achrine had little difficulty pushing away a poorly taken kick by midfielder Pele and then watching as the follow-up from Piqueti cannoned back off the crossbar.
The goalkeeper turned from villain to hero after having brought down Steve Ambri to give away the spotkick with some eight minutes left of a tepid tussle between two of the tournament's lesser lights.
A minute later Guinea Bissau striker Frederic Mendy had a powerful shot cleared off the line as Sudan held on for a share of the spoils in the Group D encounter.
Joseph Mendes had a first chance for Guinea Bissau, peeling away from the Sudan defence to find space and head a free kick against the upright in the 16th minute, but Sudan keeper Achrine was quick to gather up the rebound.
Sudan's best effort was on the stroke of halftime when Guinea Bissau goalkeeper Maurice Gomis was forced to parry away a stinging shot from Mohamed Abdelrahman.
Sudan had made a drastic overhaul of their squad just weeks before the tournament after they lost all three group games at last month's Arab Cup.
They fired French coach Hubert Velud and dropped many of their regulars ahead of the tournament.
Guinea Bissau next take on Egypt and Sudan meet Nigeria in a double header in Garoua on Saturday.
Earlier, holders Algeria were held to a surprise goalless draw by Sierra Leone as they made an uninspiring start to the defence of their Africa Cup of Nations title in Douala.
Algeria were expected to get their Group E campaign at the tournament in Cameroon off to an easy start against minnows Sierra Leone, who were returning to the tournament for the first time since 1996.
But it proved a brave showing by the West Africans as they clung on for a point in sweltering heat in the port city.
Algeria came close to opening the score in the second minute as Riyad Mahrez fed Islam Slimani, who went round the Sierra Leone goalkeeper but ran out of room to try and find the target from a tight angle.
But Sierra Leone quickly showed they would prove no easy walkover as they came storming back down the other end and were close to scoring through Alhaji Kamara's sixth minute effort.
Kamara went close with a header midway through the first half from a freekick as Algeria struggled in the heat.
Yacine Brahimi had two chances after the break to put the Algerians in the lead as they began to exert their authority, with Mahrez at the heart of their attacking moves.
His ball set Brahimi in on goal in the 52nd minute but the veteran midfielder scuffed his shot and allowed goalkeeper Mohamed Kamara to make a one-handed stop and gather at the second attempt.
Brahimi's second chance came on the hour mark but the shot was hit straight at Karama.
Sierra Leone's new cap Steven Caulker, the former England international who switched allegiance of the eve of the tournament, then made a vital block to deny substitute Sofiane Bendebka seven minutes later.
Caulker, who struggled with cramp late in the game, again denied him some 10 minutes later with another important intervention.
Mahrez’s 80th-minute effort was turned around the corner by Kamara and five minutes later substitute Said Benrahma missed a good opportunity as Algeria frustration continued amid a frenzied late finish that failed to produce a victory.
The result did, however, extend Algeria’s unbeaten run to 35 matches, putting them within touching distance of the record of 37 undefeated internationals in a row set by European champions Italy last year.
The second Group E game is being played on Wednesday in Douala when Equatorial Guinea meet the Ivory Coast.