* Long queues point to high voter turnout
* Challenger pitching economic fix to voters
* Vote looks too close to call, say analysts
* Zambia was Africa's first pandemic-era default
By Chris Mfula
LUSAKA (Reuters) - Zambians were voting for a new leader on Thursday, with long queues pointing to a high turnout in an election showdown between President Edgar Lungu and main opposition rival Hakainde Hichilema that looks too tight to call.
The two rivals, who voted at different stations hours apart, were both confident of winning the vote and the close contest raised the possibility of a run-off.
The electoral agency says it expects to declare a winner within 72 hours after polls close.
Zambia, Africa's second biggest copper producer, became the continent's first country during the coronavirus pandemic to default on its sovereign debt in November. Its economy is flagging.
Voters patiently waited in the sun to cast their ballots.
At a polling station in an affluent suburb of the capital Lusaka, crowds cheered "we want change" as Hichilema arrived to vote. The opposition leader blew back kisses to the crowd.
"Everybody must be allowed to vote. I am concerned about the speed," said Hichilema after he voted.
Earlier, Lungu was among the first voters at a station in Chawama township in the capital. Wearing a black leather jacket, a white face mask and accompanied by his wife, he waved to a cheering crowd as he left in his motorcade.
"We are winning, otherwise I wouldn't have been in the race if we were not winning," Lungu told reporters.
Some voters walked to polling stations with chairs, a Reuters journalist said, while others shared pictures of long queues on Twitter.
In the Kabwata suburb of Lusaka, first time voter Ben Mulenga, 19, braved the early morning cold and arrived two and a half hours before voting started because he anticipated long queues.
"The things that are happening in our country, including the bad state of the economy and the high levels of unemployment, need to be addressed," said Mulenga, a student at the University of Zambia.
Some 54% of registered voters are 34 or younger, statistics from the Electoral Commission of Zambia (ECZ) show.
That could help Hichilema, who is facing Lungu for the third time and has placed the economy front and center of his campaign, political analysts said.
Zambia's economy will be among the continent's slowest growing economies this year, the International Monetary Fund (IMF) estimates.
"As you can see we are suffering. Financially we are in crisis, definitely I want to make a change," said Cassidy Yumbe, a 41-year-old driver and father of four as he waited to vote.
Zambia owes in excess of $12 billion to external creditors and spends 30%-40% of its revenues on interest payments on its debt, credit rating firm S&P Global estimates.
In office since 2015, 64-year-old Lungu narrowly defeated Hichilema, the CEO of an accountancy firm before entering politics, in a disputed election the following year.
J.P. Morgan said the outcome of the election could meaningfully shape Zambia's medium-term economic outlook as the new president would need to deliver a credible economic reform package acceptable to the IMF and voters.
The president has touted the new road, airport and energy projects he has overseen as laying the groundwork for economic development and growth.
But so far his debt-financed infrastructure splurge has failed to pay economic dividends, and unemployment remains high. (Writing by MacDonald Dzirutwe; Editing by Joe Bavier, Raju Gopalakrishnan, Elaine Hardcastle and Angus MacSwan)