Afcon 2021: What we've learned from group stages in Cameroon

The Africa Cup of Nations round of 16 begins on Sunday, following a group stage which provided two major shocks, history on the field and several off-pitch talking points.

The tournament has come to life following a slow start, which saw nine 1-0s and two goalless draws in the first round of group matches.

Here BBC Sport Africa assesses the opening 12 days of action in Cameroon.

Favourites emerge?

Two teams have stood out so far: the hosts and Nigeria.

The Super Eagles are the only side with a 100% record, a statistic made all the more surprising by the fact they dismissed long-serving boss Gernot Rohr just four weeks before the tournament.

Yet the side have gelled well under interim coach Augustine Eguavoen, dominating seven-time champions Egypt in their opening game and going on to beat Sudan and Guinea-Bissau comfortably.

After an underwhelming World Cup qualifying campaign so far, the West Africans are a side to watch.

Cameroon, meanwhile, enjoyed fine wins over Burkina Faso and Ethiopia to top Group A, with skipper Vincent Aboubakar netting five goals to equal a tournament scoring record for the Indomitable Lions.

Heavyweights have contrasting fortunes

The biggest storyline on the pitch has been the unceremonious exit of defending champions Algeria.

The North Africans drew 0-0 with Sierra Leone in their opener, then lost against Equatorial Guinea before being soundly beaten by Ivory Coast.

Four-time champions Ghana were also dumped out, finishing bottom of Group B after a stunning 3-2 defeat by debutants Comoros.

Senegal, among the pre-tournament favourites, finished top of Group B despite only managing to score one goal.

The Teranga Lions were without goalkeeper Edouard Mendy and captain Kalidou Koulibaly for their first two games because of Covid-19, and their performances will surely improve.

Another side struggling to find the back of the net have been Egypt.

Mohamed Salah's Pharaohs drew a blank as they lost to Nigeria and then could only beat Guinea-Bissau and Sudan 1-0 - although they hit the woodwork three times against the Djurtus.

Do not underestimate anyone

The tournament has provided two seismic shocks.

Debutants Comoros reached the last 16 following a famous win over Ghana

Equatorial Guinea belied being 85 places below Algeria in the world rankings to end their 35-match unbeaten run which stretched back to October 2018.

Then came Comoros's first Afcon goals and maiden win over 10-man Ghana, giving the side ranked 132nd in the world a famous scalp which ultimately saw them qualify for the last 16 as one of the best third-placed teams.

The Gambia, the other first-timers in Cameroon, qualified for the last 16 after winning their opening game against Mauritania, grabbing a late draw against Mali and also beating Tunisia.

Malawi also made the knockout stages with some enterprising football, being narrowly beaten by Guinea before beating Zimbabwe and securing a draw with Senegal.

Some organisational hitches

Cameroon should have held the 2019 Nations Cup, but slow preparations delayed the arrival of the continental showpiece.

Despite the time and vast expense spent on hosting, the major disappointment has been the state of the pitch at Douala's Japoma Stadium.

Only opened in 2020, the surface has proved virtually unplayable at times - prompting scrappy games, player errors and the Confederation of African Football (Caf) to consider moving matches away from the 50,000-seater stadium.

Another moment of controversy came when Zambian referee Janny Sikazwe blew for full-time 13 seconds early in the Mali-Tunisia game - but Caf rejected Tunisian protests.

A more positive officiating story came when when Rwanda's Salima Mukansanga became the first woman to take charge of a men's Nations Cup game, refereeing Zimbabwe's win over Guinea.

Attendances building despite restrictions

Nations Cup matches which do not involve the host team are often poorly attended, but crowds in Cameroon have been better than in previous tournaments, where "neutral" ties have historically struggled to attract interest.

Because of the coronavirus pandemic crowds have been capped at 80% of capacity for Cameroon games and 60% for all others.

But after low attendances for early games in Bafoussam, Douala and Limbe, Cameroon's prime minister ordered schools and civil servants to finish early so that they could attend games.

Local people have complained about the cost of tickets, and the long queues for the compulsory Covid tests - although the stipulation regarding proof of negative tests is not always enforced. Yet fan parks, which do not require the rigmarole of lateral flow tests, have been well attended.

For the delegations themselves, it has been nigh-on impossible to avoid Covid cases. Cape Verde, Malawi and Tunisia have been among the hardest hit - but all three managed to reach the last 16, and all games have gone ahead as scheduled.

Security concerns remain

Security was a major concern on the eve of the tournament because of the separatist demands of the south-west region of Cameroon, where the city of Limbe is hosting eight matches, but the tournament has been largely unaffected so far.

A small improvised explosive device went off before the tournament, while on the first day of games in Limbe two individuals were shot dead in nearby Beau in incidents believed to be unrelated to the Nations Cup.

There was a visible security presence inside Olembe Stadium for the opening match

At the same time, the leader of local militants who have clashed with the Cameroonian army since 2017 issued another warning, declaring: "You people think that you have taken all the security measures but wait and see what will happen."

Armed groups - who argue that the Anglophone regions of Cameroon have been marginalised by the primarily French-speaking government - hope to form a breakaway state called Ambazonia.

Two Algerian journalists were subject to a knife attack in a mugging outside their hotel in Douala in the opening week, while teams have been more affected by breaches of security within their own camps.

Meanwhile, Gabon captain Pierre-Emerick Aubameyang - who has not played in Cameroon after testing positive for coronavirus - took to social media to deny widespread reports he had returned late to camp after a night out drinking.

The Arsenal striker returned to his club for further tests on what the Gabon FA described as "heart lesions" but he declared he was "completely healthy" on Thursday.