The Major League Soccer season begins Saturday, and all three Canadian teams should be in for an interesting campaign. The league's website's preseason power rankings aren't very high on the prospects of the Vancouver Whitecaps, Toronto FC or the Montreal Impact, ranking them 10th, 14th and 19th (out of 19 teams) respectively, and that's annoyed players in Montreal in particular. Each of those teams does face substantial questions, though, and there's also an overarching question about MLS in Canada; the league has decided to lock out its referees, and while that carries questions in the U.S. about how well replacement refs will do (as we saw with the NFL, there may be a notable drop-off), in Canada it raises questions about if replacement officials will even be allowed to work games north of the border given Canadian labour codes' stricter rules on replacement workers. Presuming that gets sorted out, though, there are still plenty of on-pitch issues around each Canadian side this year. Here's a key question each team will have to answer, in order of those power rankings' projected finishes.

Vancouver Whitecaps:

2013 record (points, wins-losses-draws, goals for/goals against, placing): 48 points, 13-12-9, 53/45, 7th in West

First 2014 game: Saturday, May 8, at the New York Red Bulls, 7:30 p.m. Eastern, TSN.

Key question: How will they replace Camilo's scoring?

The Whitecaps suffered perhaps the most notable loss of any MLS team this offseason, with Brazilian striker Camilo Sanvezzo ditching the team (despite the club option they held on him) to sign in Mexico. While the Whitecaps eventually received a sizeable transfer fee, it will be awfully tough for them to replace Camilo's production. He led all of MLS with 22 goals last season and made just $247,500, so it will be extremely difficult to find someone who can fill the net at that rate, and even tougher to find someone who can do so with a minimal cap hit. There are still some solid attackers on the Vancouver roster, including veteran Scottish forward and designated player Kenny Miller, new Uruguayan additions Sebastian Fernandez and Nicolas Mezquida, and a promising group of returning young players that includes Jamaica's Darren Mattocks, Gambian Kekuta Manneh and Americans Omar Salgado and Erik Hurtado, but none of them have filled the net at a rate anything close to what Camilo did last year. Of course, there's a chance the Brazilian could return to MLS given that his Mexican club is in major financial trouble and he's reportedly not getting paid, but he'll apparently have to go through the allocation process and would be unlikely to return to Vancouver given the burned bridges. We'll see how the Whitecaps do without him.

Toronto FC:

2013 record: 29 points, 6-17-11, 30/47, 9th in East

First 2014 game: Saturday, March 15, hosting the Seattle Sounders, 4:30 p.m. Eastern, TSN/NBCSN.

Key question: How will their big acquisitions do?

Toronto FC made some of MLS' splashiest moves this offseason, bringing in English striker Jermaine Defoe from Tottenham and American midfielder Michael Bradley from AS Roma. Both look like excellent acquisitions who could help to turn TFC around. However, big-name players haven't always done well in Toronto (see Mista), and even some of the ones who have played decently haven't had enough support to improve the club's record (see Torsten Frings). Depth is still going to be a concern for TFC this year, so these acquisitions won't solve everything. If Bradley and Defoe can maintain their level of play they showed overseas, though, they could give Toronto a much-needed boost.

Montreal Impact:

2013 record: 49 points, 14-13-7, 50/49, fifth in East

First 2014 game: Hosting Dallas, 8:30 p.m. Eastern Saturday, March 8, MLS Live.

Key question: How will they replace Alessandro Nesta on defence?

Despite their impressive 2013 record and playoff berth, the Montreal defence was surprisingly porous in 2013, allowing 49 goals against (fifth-worst in the league and the worst mark of any playoff team). Now, it's lost its biggest star and perhaps its most crucial piece, Italian defender Alessandro Nesta (who retired in the offseason). Can the Impact find a way to replace him? They haven't made many notable moves yet, but are reportedly pursuing American defender Heath Pierce, who could help. That defence is going to have to get better for Montreal to find success again, though, and it may be difficult without Nesta.