Team GB fell to an agonising defeat to the European champions in front of another partisan home crowd at the Olympic Park Basketball Arena.
The loss was a third straight defeat for Team GB, who can take plenty of heart from another much-improved performance against a side ranked second in the world.
"They are such a good team. We knew they were going to make runs. Basketball is about making runs and managing that momentum," Stewart said.
"We got sucked in and their shooters had so much time to hit the threes. It's hard to handle and try to come back from.
"We traded baskets all game but we couldn't get one when we needed it in the last couple of minutes. We are really struggling with those last three minutes."
Team GB took advantage of a slow start by their opponents and led 12-2 midway through the first period.
But the Russians were always going to come back stronger and after finding their range from the three-point line, they went in at half-time 39-27.
Far from letting the big stage get the better of them, Great Britain put up a spirited fight in the second half, winning both the third and the fourth period with back-to-back baskets from top-scorer Natalie Stafford cutting away at the Russian lead.
When Jo Leedham dragged her side to within three points of the lead with less than a minute on the clock, the crowd at the Basketball Arena sensed a shock might be on the cards.
But Russia held their nerve and were able to rack up nine more points as the seconds ticked away to run out 61-67 winners.
Team GB still have France and Brazil – ranked fifth and sixth respectively – to play but Stewart is still confident they can make it out of the group stages.
"We still have two games and still have a chance to get through. We are lucky in that we still have a chance unlike in some sports like judo where it is one and done," she said.
"This could be a blessing in disguise. France and Brazil are still beatable."
France virtually assured themselves a berth in the quarter-finals of the Olympic women's basketball tournament, notching their third win of the preliminary round with a hard-fought 64-60 victory over Canada.
In becoming the first team to register a 3-0 record during the five-game preliminary round with their win in the opening game of the day, France took a commanding position in Group B standings that determine seeding for games in the last eight.
China later won their third game in the six-team Group A with a 76-52 victory over Angola (0-3).
A sleepy-eyed Emilie Gomis, unaccustomed to the 9:00 a.m. start, still managed to lead France with 16 points. Shona Thorburn was high scorer for Canada with 17 points.
"It's very hard to play so early in the morning," said shooting guard Gomis, who was sharp enough to make six of her eight shots.
"I slept very little last night, I couldn't sleep. I've got a rhythm which I'm used to. When you sleep little, then you have difficulty waking up in the morning."
Canada's Natalie Achonwa, who scored 14 points and pulled down eight rebounds, said it was frustrating to lose the close game.
"We showed the tenacity of our team but we have to play the full 40 minutes."
Canada's French coach Pierre Vincent said advancing to the next round was just the first order of business, noting that the final group placings were crucial to avoid an early encounter against the heavily favoured US team, winners of the last four Olympic titles.
"If we are qualifying in the fourth position (of the group) it's not too good for us, so we have to wait until the end of the competition," Vincent said. "We want to avoid the United States and for the moment we don't know what it will be."
China still have a game to play against the US (2-0), who close Wednesday's programme against Turkey. In the quarters, the top-seeded team from each group plays the fourth seed from the other group to advance to the semi-finals.
Relying on defence and strong rebounding, Canada (1-2) kept it close, trailing by one point after the first quarter, by three at halftime and by two heading to the fourth quarter.
France had a seven-point lead with 17 seconds left but had to escape one last Canadian comeback as they closed to within 62-60 with nine seconds left.
"I think we played well. I'm very proud of how we played," said Canada coach Allison McNeill. "I would have loved for us to make a couple more shots."
Canada shot 35 percent from the floor and missed all 11 of their three-point attempts.
"We were 0-for-11 from the three for a reason. They get to you quicker, they're longer."
McNeill said she thought France could go far.
"I think France is as good as any team here. I think they have size and quickness that can match up with anyone in this tournament, including the Americans," the Canadian coach said.
"If I had to say, I think the Americans are a step above everybody here but on a given night, anybody can beat anybody."
The US later saved their long Olympic winning streak by turning a close game against Turkey into an 89-58 rout.
Angel McCoughtry led the winners with 18 points while fellow bench player Lindsay Whalen added 14 points and matched her team mate with seven rebounds to help make it 36 Olympic victories in a row dating back to 1992.
"That second group comes in and brings energy," McCoughtry said after the Group A game.
"When we sub we don't lose anything. When the other team subs they lose something. That's our secret weapon."
Coach Geno Auriemma, whose team improved to 3-0 in the preliminary round, agreed that the second wave of players often turns the tide.
"Lindsay is kind of the captain of those commandos that come in," Auriemma said. "They kind of change the tempo of the game and that's exactly what happened again tonight.
"She's a great leader and I think McCoughtry was the difference in the game."
Trailing by one point in the first quarter, the US rebounded to lead by 15 at the intermission.
Turkey, who also entered the game with a 2-0 record, reduced the deficit to 50-45 in the third quarter before the Americans went on a 13-2 run to restore order.
In the opening game of the night programme, Czech Republic beat Croatia 89-70 involving two teams who started with 0-2 records in Group A.
Czech coach Lubor Blazek was visibly upset later, saying an international basketball federation official had criticised him for taking a timeout with less then two seconds left on the clock.
"He said I was trying to humiliate our opponent but I was only trying to add points in case that was a tiebreaker for group placings," Blazek said through a translator.
"I'm sorry to say that this is the worst feeling I am having right now. This is something that is blurring the enjoyment of the victory."
Meanwhile, Australian captain Lauren Jackson led the Opals to a 67-61 victory over Brazil.
Jackson, a 6-foot-4 (1.95 m) power forward, top-scored for Australia with 18 points to take her Games career total to 497. She is competing in her fourth Games since first appearing at the 2000 Sydney Olympics in her home country.
The victory lifted Australia's record to 2-1 in the Group B preliminary round. Brazil fell to 0-3.