VANCOUVER, British Columbia -- Both the Vancouver Canucks and Buffalo Sabres are in a defensive state of mind these days -- but for different reasons.

The unbeaten Canucks (3-0-0) hope to maintain their strong defense as they host Buffalo (1-1-1) on Thursday night at Rogers Arena. On the other hand, the Sabres (1-1-1) are seeking to improve play in their own end. Vancouver has allowed only five goals against, while Buffalo has surrendered 10.

"We're not giving up nearly as many shots in the home plate area, which is just in front of the net," said Canucks center Bo Horvat. "We're generating a lot more off our turnovers and tracking back and stuff like that. Structurally, we're way better this year."

The Canucks continue to defy their critics, many of whom picked them to finish last in the 30-team NHL this season. With Tuesday's comeback 2-1 overtime victory over the St. Louis Blues, the Canucks have won three straight games when trailing after two periods. The three comeback wins already match Vancouver's 2015-16 total for wins when trailing after 40 minutes.

But Canucks coach Willie Desjardins wants more evidence of defensive dependability.

"We have worked at it," said Desjardins. "That was one of the things going in (this season), that we were going to take away some chances. (But) three games isn't a big enough sample size. We've got to keep proving it every day."

Along with consistent play from defenseman and steady two-way play by forwards, strong goaltending has been a key factor in Vancouver's quick start. But most of the saves have come from supposed backup Jacob Markstrom, who will make his third straight start. Markstrom is pulling No. 1 duty, because Ryan Miller was feeling "tight" Tuesday morning prior to his cancelled start against St. Louis.

As a result, the Canucks had to sign University of British Columbia goaltender Matt Hewitt to a one-day contract as an emergency backup.

"(The tightness) is something that, over the course of the season, you feel numerous times," Miller said Wednesday after taking part in practice. "But once you're able to get that rest, you're fine the next day. It just held on a little bit longer (this time)."

Miller said he should be available for "more exercise" Thursday. The Canucks did not announce a call-up from their AHL farm team in Utica, N.Y. He had a "slow" start to practice, but was able to stay on the ice late.

"I tried to react to shots rather than take scripted shots," said Miller. "It's reacting a lot better than I expected. It's not an injury. It's more a muscle didn't want to settle down after overtime and the shootout (in Saturday's opening win against Calgary.)"

Although the Canucks are not widely expected to make the playoffs, they have already set an NHL record this season. Vancouver has posted each win despite never having held the lead beforehand.

But coach Desjardins was not overly impressed with the record.

"We can't keep playing that way," he said. "We are not going to keep winning if we are behind in the third."

Meanwhile, the Sabres aim to stop squandering late leads. Buffalo led twice in the third period Tuesday in Calgary, but still fell 4-3 in overtime.

"Going forward, there's a lot more we have to improve on," said Sabres center Ryan O'Reilly, who was beaten on the winning goal and missed a number of scoring chances. "We did not have the jump or the compete (level Tuesday). It's embarrassing."

Winger Marcus Foligno said the Sabres have to make sure that they are "up" for their meeting with the Canucks.

"We can't hang our heads too low," he said. "But it's definitely something where we've got to go into Vancouver now and finish off a good road trip."