The karate black belt, nicknamed for her Thatcher-like resolve, is poised to win a second term as many here who remember Soviet times see her as a their best hope amid Europe's worst standoff with Moscow since the Cold War.
A former EU budget chief, the 58-year-old Grybauskaite is likely to score over 50 per cent of the vote, recent opinion surveys showed, but low turnout could trigger a May 25 run-off in this EU and NATO member country.
"If turnout exceeds 50 per cent, she has quite a good chance of scoring a first round victory," Ramunas Vilpisauskas, a political scientist at Vilnius University, told AFP.
A candidate must win half of the votes cast with a turnout of at least 50 per cent to win in round one.
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In 2009, Grybauskaite captured a resounding 69.04 per cent of the vote in the seven-candidate first round with turnout at 51.67 per cent.
This election comes as Russia's takeover of Ukraine's Crimean peninsula and sabre rattling in the neighbouring Russian exclave of Kaliningrad have sparked palpable fear in Lithuania, a country of three million.
"I can hear explosions during exercises, and windows often rattle - I don't feel very secure," the 23-year-old told AFP in the border town of Vilkaviskis.
Grybauskaite first urged and then welcomed the arrival of American troops last month as NATO stepped up its presence in the Baltic states, which spent five decades under Soviet occupation until 1991.
Lithuania along with Baltic minnows Latvia and Estonia all are keen to see more alliance 'boots on the ground' amid the Ukraine crisis.
"If there's a problem, I'll never flee abroad. I'll take a gun myself to defend the country if that what's needed for national security," she said as campaigning wound down Thursday.