By Adam Burrows, Boston.com Correspondent

BATA, Equatorial Guinea -- You can't blame President Teodoro Obiang Nguma Mbasongo for being a little suspicious.

A few years back, a band of South African mercenaries, bankrolled by London financiers and backed by Margaret Thatcher's son, were arrested in Zimbabwe as they prepared to launch a coup and install a government in Equatorial Guinea more sympathetic to their business interests.

Perhaps that explains the response to visitors as the only Spanish-speaking nation on the continent hosts AFCON 2012.

Equatorial Guinea refused to grant visas in advance of the games, insisting travelers first pass through co-host Gabon.

The Zambian team was forced to relocate from its hotel for lack of water.

On the day of the opening match, gun-toting police guarded the well-paved four-lane roadway to the Bata stadium, stopping taxis two miles away and forcing passengers out on foot.

Then, as the opening ceremonies started, armor-clad riot police fired tear gas into restless local ticket-holders lined up single-file beyond an outer gate before Israeli security advisors ordered the gate opened.

None of this came as a surprise.

In 1996, prospectors discovered vast oil reserves in Equatorial Guinea, a sliver of land and mini-archipelago flanking the equator in central Africa.

Imagine an impoverished banana republic suddenly drenched in petrodollars.

The discovery catapulted the tiny nation to the highest per capita income on the continent, though much of it is thought to have ended up in the pockets of the president, named by Human Rights Watch as one of world's worst dictators.

On the other hand, the President has a generous side.

The headlines in El Lector, the official mouthpiece of the regime, proclaimed the promise of $1 million to the national team if they defeated Libya in the opening match.

The players, most of them controversially naturalized ringers of questionable Equatoguinean ancestry recruited from Iberia and Africa, did not disappoint.

In the final minutes, Portugal-based captain Juvenal sprung Spain-based Javier-Angel Balboa behind the Libyan back line. Balboa finished cleanly into the right corner and dismissed suggestions that the bonus offer was a motivating factor: "This is football. When the match starts, the players don't think about money. Many players play in Europe. We get money from our clubs. To us, the money is not very important."

President Obiang also treated the audience to an over-the-top opening ceremony, featuring drummers, dancers, and images of African culture projected on a 60-foot high hexagonal monolith at the center circle, concluding with a delirious fireworks display that ringed the crest of the stadium.

Few in the capacity crowd of 37,500 stuck around to watch Zambia stun favored Senegal 2-1 in the nightcap. The speedier and more creative Chipolopolo (Copper Bullets) started brightly and beat former Colorado Rapids and New York Red Bull goalkeeper Bouna Coundoul twice in the opening twenty minutes.

Four days later, the stadium was again nearly empty as a deluge delayed the start of the Libya-Zambia match for over an hour and reduced the pitch to a waterlogged marsh.

The conditions slowed down the Chipolopolo, who had to battle back twice to earn a 2-2 draw, as Libya's 32-year-old Osman, seeming to glide on water while Zambian defenders slipped in his wake, notched an impressive brace.

The red-clad local fans were back in force for the second game, while Senegal, heavy pre-tournament favorites to take the group, looked to get on track.

It was not to be.

Following a scoreless first half, Equatorial Guinea took the lead on a Iban Iyanga header off a David Alvarez cross, then, after Niang Sow equalized, scored the upset of the tournament on a long-range Alvarez screamer as injury time expired.

The unheralded Nzalang Nacional become the first team to advance to the knockout stage, while the mighty Lions of Teranga, eliminated without a point in two games, are left to lick their wounds. Zambia, with four points, can advance with a draw against Equatorial Guinea on Sunday.