Duda is running for a second term as Polish president while Warsaw mayor Trzaskowski has seen his stock rise in recent months.
Poland's outgoing president Andrzej Duda failed to win an outright majority in Sunday's presidential election and is set to face Warsaw mayor Rafal Trzaskowski in a July 12 run-off.
According to an Ipsos projection, Duda won 41.8% of the vote and Trzaskowski 30.4%.
The official results should be released on Wednesday evening after votes sent from abroad are counted.
"If these results are confirmed, we are set for a very tight run-off," Paweł Zerka, a policy fellow at the European Council on Foreign Relations, told Euronews, adding that a defeat for Duda could even pave the way for a snap election, given the tight majority of the ruling, Duda-allied Law and Justice party (PiS).
Here is an analysis of how the election could play out and what's at stake.
Who is the incumbent and is he likely to be reelected?
Incumbent Andrzej Duda is running as an independent candidate allied with PiS and seeks a second term after being first elected in 2015.
The 48-year-old president has centred his campaign around his strong track record with PiS and on the promise of stability and prosperity, pledging at the same time big infrastructural projects.
He and PiS are credited with introducing welfare programs that lifted many Poles out of poverty, such as a monthly €111 wage for each child under 18 regardless of the family income.
But the ruling party was condemned by Brussels for controversial judicial reforms that critics say allows the government to influence the top courts and other key judicial bodies. PiS, however, claimed the changes were necessary to eradicate corruption among judges.
More recently, Duda prompted wide criticism from the country's activists for comparing the LGBT "ideology" to Bolshevism, during a rally.
"First round results indicate that there is a much simpler arithmetic for Duda than Trzaskoski," Angelos Chryssogelos, lecturer in Politics and International Relations at London Metropolitan University, told Euronews.
"One of the election surprises was [the result for] young radical (Krzysztof) Bosak, well to the right of PiS on both social and economic matters. Updated election results show that the combined vote of Bosak and Duda is already above 50 per cent with a number of smaller right-wing candidates providing a further reservoir of votes," he added.
But for Anna Gwiazda, senior lecturer in Comparative Politics at King's College London, Duda's potential to attract voters beyond PiS "is limited".
"Duda already appealed to (Bosak's) Confederation voters to back him. However, the Confederation is sceptical of Law and Justice and often criticised the governing party," she noted.
Trzaskowski 'has not lost the battle yet'
Duda's main competitor is Warsaw mayor Rafal Trzaskowski, from the main opposition centre-right Civic Platform, known as Platforma Obywatelska (PO) in Poland.
PO supports civil unions for same-sex couples, opposes tightening Poland's already strict abortion law and calls for restoring state support for in-vitro fertilisation.
The party governed from 2007 to 2015 overseeing a strong economic growth, but it was also criticised for pro-market policies that increased economic inequality instead of addressing poverty.
Trzaskowski has promised to keep Law and Justice’s popular social welfare spending programmes but vowed at the same time to restore constitutional norms and improve ties with the EU.
To win, he will need to be "endorsed by other opposition candidates such as Hołownia (independent), Kosiniak-Kamysz (Polish Peasant Party) and Biedroń (the Left)," Gwiazda stressed.
But he will also need "to campaign in small town and the countryside," she added.
Chryssogelos concurred: "First round results indicate that his, and other liberals' reach into rural bastions of PiS is extremely weak".
"There is a large voting bloc -- around a fifth of the electorate -- for moderate centre-right candidates who could vote for Trzaskowski out of concerns for democracy and PiS' radicalism but who are still too socially conservative to feel comfortable voting for a too liberal candidate. Trzaskowski must get all these votes to have a chance of winning," he went on.
A 'polarised' society
Turnout for this first round has been 62.4%, the highest in twenty years, but according to Chryssogelos, "did not favour much either camp -- especially the opposition, which was hoping that higher mobilisation would signal dissatisfaction with PiS".
This, he argued, "speaks to the fact that polarisation in Polish society is very real, reflecting deep value divides on a range of issues like social lifestyles, Europe and national identity."
For Gwiazda, the high turnout shows that the Poles are now "becoming more active, which is a positive development for the Polish democracy".
"But it also shows that the country is deeply divided and issues are contested which mobilised some voters".
A tale of two Polands
The next two weeks of campaigning should, therefore, see the two candidates offer two very contrasting visions for the country.
"The competition is really about symbols and values," Chryssogelos highlighted.
"Duda speaks a lot to traditional understandings of family, religion and patriotism, while presenting himself as the guarantee that the government's generous welfare policies will continue. For Trzaskowski voters the election is about keeping PiS from dominating all levers of power so that Poland doesn't turn into Hungary, and realigning Poland with EU values and priorities," he added.
As such, Gwiazda flagged, "in the coming days we can expect a bitter campaign dominated by two different visions of Poland and demonstrating that Poland is divided in half."
Limited presidential powers
Poland's president has few legislative powers but they have the right to veto any law passed by parliament.
The veto can be overturned by a three-fifths majority in parliament's lower house.
However, the ruling coalition, United Right, only holds a majority of five seats, which makes the president's veto even more important.
The ballot was initially scheduled on May 10 but got postponed because of the coronavirus pandemic.
This is the second major election happening in Europe after the continent was struck by the coronavirus pandemic.
It follows Serbia's parliamentary election on June 21, which saw a 48% turnout.