The battle for Bakhmut, the Ukrainian city which Russia has spent months trying to capture, is "stabilising", says Ukraine's commander-in-chief.
alerii Zaluzhnyi said Ukrainian troops' "tremendous efforts" were holding back Russia.
Earlier this month, Western officials estimated between 20,000 and 30,000 Russian troops had been killed or injured in Bakhmut since last summer.
Moscow is eager for a victory after failing to make major recent gains.
Despite this, military analysts believe Bakhmut has little strategic value, with the city's importance now symbolic.
The high number of Russian casualties may be the main reason Ukraine has not withdrawn from the city, analysts say.
On Facebook, Lt Gen Zaluzhnyi said that while the situation on Ukraine's frontlines "is the toughest in the Bakhmut direction... due to the tremendous efforts of the defence forces, we are managing to stabilise the situation".
Lt Gen Zaluzhnyi posted after speaking to the UK's Chief of Defence Staff, Admiral Sir Tony Radakin, about the situation in Ukraine.
His comments are the latest positive signal from Ukrainian officials about the long battle for Bakhmut.
The UK's Ministry of Defence said on Saturday that Russia's assault on Bakhmut has "largely stalled", citing "extreme attrition" of the Russian force as a cause, and added that Russia has likely shifted its operational focus to the south and north of Bakhmut.
Such moves might suggest an "overall return to a more defensive operational design" after Russia failed to achieve significant results from its attempts to conduct a general offensive since January, the UK said.
Earlier this week, Oleksandr Syrsky, commander of the country's ground forces, said that Russian troops were "exhausted" near Bakhmut.
Mr Syrsky added that while Russia had "not given up hope of taking Bakhmut at all costs despite losses in manpower and equipment... they are losing significant strength".
And Ukrainian President Volodymyr Zelensky recently visited the frontline near Bakhmut, where he last visited in December.
Footage showed him in an old warehouse giving medals to soldiers, whom he called "heroes".
The Institute for War, a think tank, said on Thursday that although Ukraine is still outnumbered by the Wagner group, Ukrainian forces "continue to exhaust the mercenaries, which will enable Ukrainian forces to pursue unspecified future offensive operations".
Wagner, a private, mercenary organisation, is at the heart of the Russian assault on Bakhmut. Its leader, Yevgeny Prigozhin, has staked his reputation on seizing the city.
The MoD said the Russian situation in Bakhmut was likely worsened by tensions between Wagner and the Russian Ministry of Defence.
About 70,000 people lived in Bakhmut before the invasion, but only a few thousand remain.