Malaysians voted on Sunday with one of the world's longest-serving governments facing the possibility of defeat for the first time against an upstart opposition that pledges sweeping reform.
Voting started at 8:00 am (0000 GMT) at more than 8,000 polling centres nationwide after a bitter campaign in the multi-ethnic country, marked by opposition charges of election fraud and widespread violence.
The supremacy of the ruling bloc dominated by the United Malays National Organisation (UMNO), and now led by Prime Minister Najib Razak, has never been threatened since independence in 1957.
But the diverse opposition captained by charismatic former UMNO star Anwar Ibrahim stunned the country by making unprecedented gains in 2008 polls and Sunday's vote has been keenly awaited ever since.
The ruling coalition is widely given the edge but recent opinion polls suggest a race too close to predict, as Anwar has been feted by crowds in the tens of thousands on the stump for his three-party Pakatan Rakyat alliance.
"There is clearly, undeniably, a major groundswell and a major shift among the population across ethnic lines," Anwar, 65, said after he cast his ballot in a polling centre in his constituency in the northern state of Penang.
Lines of up to one kilometre (0.6 miles) long and waits in excess of two hours were reported at some polling stations as voters took advantage of clear weather and cooler morning air. Analysts say high turnout may boost Pakatan.
Pakatan has capitalised on anger over corruption and authoritarianism, which it vows to end, and controversial affirmative-action policies for majority ethnic Malays.
Anwar, who says the policies are abused to prop up an arrogant Malay elite, vows to end such race-based politics, reaching out to minorities and a younger generation raised on the alternative views found online.
His back to the wall, Najib has offered limited political reforms in a largely stay-the-course vision for the Muslim-majority nation while touting solid economic growth.
The opposition has set the stage for a disputed result with numerous accusations of electoral fraud by Najib's coalition, known as the Barisan Nasional (National Front).
They include an alleged scheme to fly tens of thousands of "dubious" and possibly foreign voters to key constituencies to sway results. The government denies wrongdoing.
Indelible ink applied to voters' fingers to prevent multiple voting -- touted by Najib as a safeguard against fraud -- was found last week to wash off easily.
But the Election Commission, widely viewed as Barisan-controlled, has brushed off any concern.
After voting at Anwar's polling centre, Halim Mohamad, 77, said the ink, supposed to last several days, washed right off.
"This is cheating. I was shocked when it came off," he told AFP, showing his cleaned index finger.
"I complained to an Election Commission official and he just laughed."
Anwar was a former deputy premier until his ouster in a 1998 power struggle and six-year jailing on sex charges, widely viewed as trumped up.
He later brought his pan-racial appeal to the once-divided opposition, dramatically changing its fortunes.
Najib has played on fears of instability, warning of chaos and racial strife under Pakatan, which includes Anwar's multi-racial party, one led by ethnic Chinese, and another representing conservative Muslim Malays.
Najib's ethnic Malay-dominated regime retains powerful advantages, including control of traditional media and an electoral landscape critics say is biased.
Campaigning has been marred by hundreds of reports of violence, intimidation, arson and two small explosions, although no deaths have been reported.
Polling stations close at 5:00 pm (0900 GMT) with first results expected within hours.
"It's a tight run. But I'm not scared, I'm excited," said retiree H.Y. Ong, as he waited to vote in the capital Kuala Lumpur.
"The times have changed, they (the government) need to change. Money politics should be controlled," he added, while not divulging his voting preference.