Juniors

As a junior Lacko compiled a singles win–loss record of 88–39, reaching as high as No. 3 in the combined junior world rankings in February 2005.

Junior Grand Slam results:

Australian Open: QF (2005)
French Open: SF (2005)
Wimbledon: 1R (2004)
US Open: 2R (2005)

Professional tour

At the 2010 Australian Open, he lost in the second round to World No. 2 and defending champion Rafael Nadal 2–6, 2–6, 2–6.^[2]

At the 2010 French Open, he played and won the longest match of his career in the first round against American Michael Yani with the score at 6–4, 6–7, 6–7, 7–6, 12–10. The 4-hour, 56-minutes match stretched over the course of two days, and tied the record for the most games played in the Open Era at the French Open.^[3] Lacko continued his second round streak in 2010 majors by defeating the 24th seed Marcos Baghdatis in four sets. He then lost a very tight five set second round match against Jérémy Chardy. He played in the 2010 Atlanta Tennis Championships and upset former World No.1 Lleyton Hewitt 6–2, 6–4 to advance to the quarterfinals.^[4] At the 2011 Qatar Open, he lost in the second round to Rafael Nadal, despite achieving the rare feat of winning a bagel set against Nadal.^[5]

He reached his first singles ATP final in Zagreb 2012, where he lost to Mikhail Youzhny in straight sets. At the 2012 Summer Olympics, he lost in the first round in the men's singles, and in the first round of the men's doubles with Martin Kližan.^[6] At the 2014 French Open he lost in the first round to Roger Federer.

Lacko reached his second career ATP final at the 2018 Eastbourne International losing to Mischa Zverev.^[7]

In October 2022, he announced that 2022 might be his last season.^[8]

Singles: 2 (2 runner-ups)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Loss	0–1	Feb 2012	Zagreb, Croatia	250 Series	Hard (i)	Mikhail Youzhny	2–6, 3–6
Loss	0–2	Jun 2018	Eastbourne, United Kingdom	250 Series	Grass	Mischa Zverev	4–6, 4–6

Doubles: 1 (1 runner-up)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Loss	0–1	Sep 2012	St. Petersburg Open, Russia	250 Series	Hard (i)	Igor Zelenay	Rajeev Ram Nenad Zimonjić	2–6, 6–4, [6–10]

Singles: 40 (22–18)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Loss	0–1	May 2005	Morocco F4, Marrakesh	Futures	Clay	Lamine Ouahab	6–4, 3–6, 2–6
Loss	0–2	Aug 2005	Croatia F3, Vinkovci	Futures	Clay	Marin Cilic	3–6, 1–6
Win	1–2	Oct 2005	Italy F32, Olbia	Futures	Clay	Tobias Koeck	6–1, 6–3
Win	2–2	Oct 2005	Ukraine F2, Cherkassy	Futures	Clay	Sascha Kloer	2–6, 6–3, 6–1
Loss	2–3	Oct 2005	Ukraine F3, Illyichovsk	Futures	Clay	Photos Kallias	3–6, 7–5, 1–5
Loss	2–4	Nov 2005	Czech Republic F6, Ostravicí	Futures	Hard	Jan Hajek	6–1, 5–7, 4–6
Win	3–4	Jan 2006	Austria F2, Salzburg	Futures	Carpet	Werner Eschauer	3–6, 6–1, 7–5
Loss	3–5	Jun 2006	Italy F19, L'Aquila	Futures	Clay	Kamil Capkovic	2–6, 6–7(6–8)
Win	4–5	Jul 2006	Germany F6, Kassel	Futures	Clay	Dustin Brown	3–6, 6–3, 6–4
Loss	4–6	Aug 2006	Binghamton, United States	Challenger	Hard	Scott Oudsema	6–7(5–7), 2–6
Loss	4–7	May 2007	Rijeka, Croatia	Challenger	Clay	Marin Čilić	5–7, 2–6
Loss	4–8	Aug 2007	Istanbul, Turkey	Challenger	Hard	Mischa Zverev	4–6, 4–6
Win	5–8	Oct 2007	Kolding, Denmark	Challenger	Hard	Gilles Müller	7–6(7–3), 6–4
Win	6–8	Jan 2009	Great Britain F2, Sheffield	Futures	Hard	Scott Oudsema	7–6(7–5), 5–7, 6–3
Win	7–8	Feb 2009	Croatia F2, Zagreb	Futures	Hard	Antonio Sancic	6–2, 4–6, 7–5
Win	8–8	Apr 2009	Russia F1, Moscow	Futures	Carpet	Denis Matsukevitch	6–4, 4–6, 6–2
Win	9–8	Apr 2009	Russia F2, Tyumen	Futures	Carpet	Pavel Chekhov	6–3, 5–7, 6–4
Win	10–8	May 2009	Fergana, Uzbekistan	Challenger	Hard	Samuel Groth	4–6, 7–5, 7–6(7–4)
Win	11–8	Nov 2009	Seoul, South Korea	Challenger	Hard	Dušan Lojda	6–4, 6–2
Loss	11–9	Nov 2010	Ortisei, Italy	Challenger	Clay	Michał Przysiężny	3–6, 5–7
Win	12–9	Sep 2011	Izmir, Turkey	Challenger	Hard	Marsel İlhan	6–4, 6–3
Win	13–9	Nov 2011	Bratislava, Slovakia	Challenger	Hard	Ričardas Berankis	7–6(9–7), 6–2
Loss	13–10	Oct 2012	Tashkent, Uzbekistan	Challenger	Hard	Uladzimir Ignatik	3–6, 6–7(3–7)
Win	14–10	Nov 2012	Helsinki, Finland	Challenger	Hard	Jarkko Nieminen	6–3, 6–4
Loss	14–11	Jul 2013	Granby, Canada	Challenger	Hard	Frank Dancevic	4–6, 7–6(7–4), 3–6
Win	15–11	Nov 2013	Bratislava, Slovakia	Challenger	Hard	Lukáš Rosol	6–4, 4–6, 6–4
Loss	15–12	Apr 2014	Shenzhen, China	Challenger	Hard	Gilles Müller	6–7, 3–6
Win	16–12	Oct 2014	Tashkent, Uzbekistan	Challenger	Hard	Sergiy Stakhovsky	6–2, 6–3
Loss	16–13	Apr 2015	Ra'anana, Israel	Challenger	Hard	Nikoloz Basilashvili	6–4,4–6,3–6
Loss	16–14	May 2015	Busan, South Korea	Challenger	Hard	Chung Hyeon	3–6,1–6
Win	17–14	Sep 2015	Izmir, Turkey	Challenger	Hard	Marius Copil	6–3, 7–6(7–5)
Loss	17–15	Oct 2015	Tashkent, Uzbekistan	Challenger	Hard	Denis Istomin	3–6, 4–6
Loss	17–16	Nov 2015	Bratislava, Slovakia	Challenger	Hard	Egor Gerasimov	6–7(1–7), 6–7(5–7)
Loss	17–17	Mar 2016	Guangzhou, China	Challenger	Hard	Nikoloz Basilashvili	1–6, 7–6(8–6), 5–7
Win	18–17	Nov 2017	Bratislava, Slovakia	Challenger	Hard	Marius Copil	6–4, 7–6(7–4)
Win	19–17	Nov 2017	Brescia, Italy	Challenger	Hard	Laurynas Grigelis	6–1, 6–2
Win	20–17	May 2018	Glasgow, United Kingdom	Challenger	Hard	Luca Vanni	4–6, 7–6(7–3), 6–4
Win	21–17	Oct 2019	Ismaning, Germany	Challenger	Carpet	Maxime Cressy	6–3, 6–0
Win	22–17	Aug 2021	Mallorca, Spain	Challenger	Hard	Yasutaka Uchiyama	5–7, 7–6(10–8), 6–1
Loss	22–18	Oct 2021	Ismaning, Germany	Challenger	Carpet	Oscar Otte	4-6, 4-6

Doubles: 9 (5–4)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Win	1–0	Apr 2006	Dharwad, India	Challenger	Hard	Kamil Čapkovič	Sanchai Ratiwatana Sonchat Ratiwatana	6–3, 7–5
Loss	1–1	Jun 2006	Kosice, Slovakia	Challenger	Clay	Kamil Čapkovič	Viktor Bruthans Pavel Snobel	5–7, 7–5, [4–10]
Loss	1–2	May 2007	Rijeka, Croatia	Challenger	Clay	Ivo Klec	Jean-Rene Lisnard Jerome Haehnel	3–6, 4–6
Win	2–2	Apr 2009	Russia F1, Moscow	Futures	Carpet	Konstantin Kravchuk	Pavel Chekhov Valery Rudnev	6–2, 6–4
Win	3–2	Sep 2009	St. Remy, France	Challenger	Hard	Jiří Krkoška	Ruben Bemelmans Niels Desein	6–1, 3–6, [10–3]
Loss	3–3	Oct 2009	Tashkent, Uzbekistan	Challenger	Hard	Jiří Krkoška	Denis Istomin Murad Inoyatov	6–7(4–7), 4–6
Win	4–3	Nov 2011	Bratislava, Slovakia	Challenger	Hard	Jan Hájek	Lukáš Rosol David Škoch	7–5, 7–5
Win	5–3	Oct 2014	Tashkent, Uzbekistan	Challenger	Hard	Ante Pavić	Frank Moser Alexander Satschko	6–3, 3–6, [13–11]
Loss	5–4	Jan 2020	Rennes, France	Challenger	Hard	Teymuraz Gabashvili	Antonio Sancic Tristan-Samuel Weissborn	5–7, 7–6(7–5), [7–10]

Singles

Current through the 2022 Australian Open.

Doubles