However, Macron is widely expected to gallop to victory over the divisive Front National leader and traders gave a huge thumbs-up, sending the euro flying above $1.09 at one point before paring the gains to $1.0846 from $1.0726 in New York on Friday. It also jumped to 119.40 yen from 117.07 yen.
"Markets are happy to buy what they see as the fact -- that 39-year-old Emmanuel Macron will be confirmed as the next president of the French republic in two weeks' time," Ray Attrill, head of FX strategy at National Australia Bank, said in a commentary.
The boost in optimism also hit the yen -- considered a safe bet in times of uncertainty -- which in turn lifted Japanese exporters.
US tax reform
Tokyo's Nikkei rose 1.3 percent, Sydney and Seoul each added 0.2 percent, and Wellington put on 0.4 percent.
However, Hong Kong gave up early gains and ended the morning session 0.1 percent down, while Shanghai sank almost 1.6 percent, extending a recent sell-off fuelled by profit-taking, liquidity and regulatory plans.
"Given that pre-vote polling shows that Macron should trounce Le Pen on May 7, markets are already celebrating as though Macron is already the president of The Republic," said Greg McKenna, chief market strategist at AxiTrader, in a note.
The gains in Asia extended Friday's rally that was built on comments from US Treasury Secretary Steven Mnuchin, who promised a tax reform plan would be unveiled soon.
That was followed by Trump saying Friday that there would be "a big announcement on Wednesday having to do with tax reform".
Eyes are now on Washington where lawmakers have just four days to agree a funding bill to avoid a painful government shutdown that would cost the economy billions of dollars.
There are fears Trump will refuse to sign anything that does not contain spending for his controversial Mexican border wall, with Democrats saying they will not back anything that includes provisions for the plan.
Key figures at 0430 GMT
Tokyo - Nikkei 225: UP 1.3 percent at 18,854.97
Hong Kong - Hang Seng: DOWN 0.1 percent at 24,016.23 (break)
Shanghai - Composite: DOWN 1.6 percent at 3,123.80 (break)
Euro/dollar: UP at $1.0846 from $1.0726 at 2100 GMT Friday
Euro/yen: UP at 119.40 yen from 117.07 yen
Pound/dollar: DOWN at $1.2790 from $1.2810
Dollar/yen: UP at 110.05 yen from 109.15 yen
Oil - West Texas Intermediate: UP 25 cents at $49.87 per barrel
Oil - Brent North Sea: UP 30 cents at $52.26
New York - Dow: DOWN 0.2 percent at 20,547.76 (close)
London - FTSE 100: DOWN 0.1 percent at 7,114.55 (close)
/AFP/
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