In 2006 Korolev claimed a win in Marseille over fellow countryman and world number 5 Nikolay Davydenko, but went on to lose in the quarter-finals to French veteran Sébastien Grosjean.

He then reached the semi-finals of an American contest, losing to Jürgen Melzer, after beating James Blake and Sam Querrey in the earlier rounds.

In 2008, Korolev also claimed victories over the likes of Paul-Henri Mathieu and Fernando González, and reached the quarter-finals in Sydney, losing to Frenchman Fabrice Santoro.

Again starting in qualifying, he won seven straight matches (including wins over world number 38, Igor Kunitsyn, and over Guillermo García-López) before eventually falling in the final to top seed, Mardy Fish, 7–5, 6–3.

There, he reached the semifinal, scoring wins against players such as Leonardo Mayer, Daniel Gimeno Traver, and Guillermo Cañas, before losing to the eventual champion Lleyton Hewitt 6–7, 4–6.

Korolev struggled to build on that run, with Masters 1000 defeats to Juan Mónaco and Eduardo Schwank when aiming to qualify and was also put out of Munich in straight sets to Frenchman Jérémy Chardy.

At Roland Garros, Korolev had to pull out of a match with Gimeno Traver due to an ankle problem which had also forced him out of the doubles the week prior to the event.

He has since taken part in occasional challenger events, although he admits his motivation has been hindered by the move to the lower ranks of world tennis,[citation needed] possibly contributing to losses against Pere Riba and Roberto Bautista-Agut.

In September 2009, Evgeny Korolev won the 17th Szczecin Pekao Open, defeating Albert Montañés 4–6, 6–3, 6–2 in the semi-final, and Frenchman Florent Serra 6–4, 6–3 in the final.

He played his last tournament of the year in the 2009 Davidoff Swiss Indoors as a qualifier, defeating Simone Bolelli 3–6, 7–6, 6–2 and Jérémy Chardy 6–4, 7–6, before losing to top seed Roger Federer 6–3, 6–2.

Korolev began the year at the 2010 Qatar ExxonMobil Open and the 2010 Medibank International Sydney, in both cases reaching the second round, losing to Roger Federer and Mardy Fish respectively.

At the US Open he retired against Kei Nishikori in the first round due to an elbow injury which sidelined him for the rest of the year and caused him to fall outside the top 100.

In 2011, due to his low ranking he started playing in the qualifying rounds and the challenger tour, but fell short, not being able to score back-to-back wins, until the 2011 Status Athens Open, where he reached the quarterfinals before falling to Dmitry Tursunov 7–5, 7–5.