TORONTO -- While the quest for MLS success continues, soccer has taken a back seat to real life this week for Toronto FC.

Veteran defender Drew Moor has been sidelined with a cardiac arrhythmia -- or irregular heartbeat -- ahead of Saturday's game in Columbus. Coach Greg Vanney is expected to be on the sidelines at Mapfre Stadium after missing most of this week's training due to what the club is calling a family matter.

"A weird week," said assistant coach Robin Fraser, who has been running the team in Vanney's absence.

"When anything happens to anyone on our team, I think we all band together," said defender Nick Hagglund, who regularly car-pools to training with Moor. "We all feel it in some form or fashion.

"But at the end of the day our job is to get three points, so that's our goal, and we hope the best for Drew and for Greg and that we're going to do a job for them."

All Toronto players wear heart monitors and GPS chips during practice and the team's medical staff noticed some unusual data for Moor in training earlier this week. That led to a talk with Moor, who acknowledged he had been feeling something unusual, and a visit to the team doctor and then a cardiologist.

Moor has been wearing another monitor to track exactly what is happening when the heart irregularity occurs. More tests are planned to determine the exact nature of the condition and what can be done to correct it.

"Beyond this weekend it's hard to say," Fraser said of Moor's availability. "We don't have him for (Saturday) which is unfortunate. I would hope that we would get more answers in the next few days.

In the meantime, Moor is not training. He watched practice Friday but did not speak to reporters.

"He's more bummed about not being able to play (Saturday) than anything else," said Fraser. "He's a trooper, his spirits are great. He's just looking to get on with it."

The episode is proof of the value of the devices that today's players wear in training. A $250 heart monitor and the right person checking it helped flag the problem.

"Fantastic," said Fraser. "It's great that we have the technology that we do and that we have the staff that we do -- because to just pick something up like that and have a strong enough feeling about it to go and further investigate, I think is just a great testament to the technology and how dedicated and aware our group is."

Moor, a 33-year-old Texan, has anchored the Toronto defence since joining the team prior to the 2016 season as a free agent from Colorado. TFC ranks fourth in the league in goals against, conceding a stingy 0.80 goals a game.

With Jason Hernandez and Chris Mavinga both nursing minor injuries, barring a change of formation it's likely Hagglund will move into the centre of the three-man backline with Eriq Zavaleta remaining at right centre back. Justin Morrow would shift to left centre back with Raheem Edwards replacing him as left wingback.

While one of only three unbeaten teams in Major League Soccer, Toronto (1-0-4) is looking to turn ties into wins. It is only three points behind Columbus, which sits atop the Eastern Conference.

"Columbus is a very good team," said Fraser. "Certainly we understand where we are in the standings and where they are in the standings. But it's another test for us to continue to do some things that we've done well and gotten better at over the last couple of weeks.

"They're a very good attacking team. We will be tested defensively."

The trip to Ohio is the only game away from BMO Field in a six-match segment. Toronto tied Sporting Kansas City and Atlanta United in the first two games of that stretch.

Columbus (3-2-1) was without defenders Harrison Afful (hand) and Jonathan Mensah (hamstring) and playmaker Federico Higuain (ankle) for last week's 1-0 loss to Chicago. Mensah, a Ghanaian international brought in as a designated player this season, was injured in the March 25 win over Portland. All remain questionable.

Former Whitecap Kekuta Manneh, traded March 30, could make his Columbus debut.