In the main event of UFC Fight Night 149 in St. Petersburg, Russia, on Saturday, Alistair Overeem defeated Alexey Oleynik by technical knockout in the first round of their heavyweight clash.

Overeem managed to mount Oleynik in the closing seconds of the opening round, and with Overeem raining down punches and elbows, the referee had no choice but to stop the fight:

Oleynik was aggressive in the early going with some big punches that appeared to have Overeem in defense mode:

However, it wasn't long before Overeem took control with some heavy knees that knocked Oleynik to the ground and allowed Overeem to finish him off:

ESPN's Brett Okamoto noted that Oleynik did not have enough in his skill set to overcome Overeem's power:

With the win, Overeem improved to 45-17 professionally and got himself back in the thick of the heavyweight title scene. Overeem has now won two in a row with victories over Oleynik and Sergey Pavlovich on the heels of consecutive losses to Francis Ngannou and Curtis Blaydes.

Oleynik was chosen as a replacement opponent for Overeem earlier this month after Alexander Volkov was forced to pull out with an injury.

The 41-year-old Oleynik fell to 57-12-1, and his two-fight winning streak was snapped. At the first UFC event to take place in Russia in September 2018, Oleynik was victorious over Mark Hunt, but he was unable to prevail Saturday.

In addition to Overeem's win over Oleynik, here is a rundown of the full main card and undercard results for UFC Fight Night 149 in St. Petersburg.

Main card

Alistair Overeem def. Alexey Oleynik via first-round TKO (4:45)

Islam Makhachev def. Arman Tsarukyan via unanimous decision (30-27, 30-27, 29-28)

Sergey Pavlovich def. Marcelo Golm via first-round KO (1:06)

Roxanne Modafferi def. Antonina Shevchenko via split decision (29-28, 28-29, 29-28)

Krzysztof Jotko def. Alen Amedovski via unanimous decision (30-25, 30-26, 30-26)

Undercard

Movsar Evloev def. Seung Woo Choi via unanimous decision (29-27, 29-27, 29-26)

Sultan Aliev def. Keita Nakamura via unanimous decision (30-27, 30-27, 30-27)

Alexander Yakovlev def. Alex Da Silva via second-round guillotine submission (3:10)

Shamil Abdurakhimov def. Marcin Tybura via second-round TKO (3:15)

Michal Oleksiejczuk def. Gadzhimurad Antigulov via first-round KO (0:44)

Magomed Mustafaev def. Rafael Fiziev via first-round TKO (1:26)

Islam Makhachev def. Arman Tsarukyan

In a fight that featured two Russian fighters with just one career loss apiece, Islam Makhachev outlasted Arman Tsarukyan in a unanimous-decision victory.

Makhachev and Tsarukyan were quite evenly matched, and they showed off some great technical acumen throughout the contest. Makhachev often had the upper hand because of his takedown ability, however:

Tsarukyan was on the verge of locking in some dangerous submissions on a few occasions, but he was never able to fully reel Makhachev in:

While Tsarukyan was 13-1 entering Saturday's fight, he was making his UFC debut and doing so in his home country of Russia, which may have added some pressure to the moment. Meanwhile, Makhachev was no stranger to the spotlight with six previous UFC bouts to his credit.

With the win, Makhachev now owns one of the longest active winning streaks in the UFC lightweight division with five victories in a row:

Makhachev's last loss was at UFC 192 in 2015 against Adriano Martins, but he has shown no ill effects since then.

Given his recent run of success, Danny Segura of MMA Fighting believes it is time for UFC to feed him a top-tier opponent:

UFC has brought Makhachev along slowly thus far, but based on Saturday's performance, he is ready for another step up in competition his next time out.

Roxanne Modafferi def. Antonina Shevchenko

Antonina Shevchenko suffered the first loss of her professional MMA career Saturday via split decision to American Roxanne Modafferi in a women's flyweight fight.

Modafferi got the better of Shevchenko in the ground game, as she managed to take down and mount the 34-year-old Russian star in front of her home crowd on multiple occasions:

According to ESPN's Ariel Helwani, Shevchenko was the more effective striker, but Modafferi's ability to neutralize her on the ground was the difference in the fight:

There was some controversy surrounding the decision because of the fact that one judge scored the fight for Shevchenko. While Shevchenko had her moments in standing positions, she spent much of the bout on her back.

Two judges saw enough out of Modafferi to award her the victory, which allowed her to bounce back from a UFC 230 loss to Sijara Eubanks.

The 36-year-old Modafferi has proved to be a difficult opponent for UFC's up-and-coming fighters in recent years, and Fightful's Sean Ross Sapp pointed out how remarkable it is considering her struggles from 2010 to 2013:

Modafferi has settled into her role as a gatekeeper, and she did not allow Shevchenko to pass in what was the biggest fight of Shevchenko's career.

After the win, Modafferi joked that she wanted to face Cris Cyborg next:

While a bout against Cyborg is unlikely, Modafferi earned herself another UFC fight in the near future, and perhaps another opportunity to spoil things for a rising star.