The fortunes of Los Angeles' two Major League Soccer clubs could not be more contrasting as they head into Sunday's first derby of the season.

Los Angeles FC are the defending MLS champions, are third in the Western Conference, unbeaten this season, and booked their place in the semi-finals of the CONCACAF Champions League in midweek.

The winless Los Angeles Galaxy are next to bottom in the West, with just three points, and this week their club president Chris Klein promised he would stand down if the team fails to reach the playoffs.

Galaxy fans are protesting, boycotting games and demanding Klein quits his job right now and the stress was showing on head coach Greg Vanney as he resorted to swearing on several occassions in his weekly press conference.

Vanney insists his team's poor start to the season is at least in part explained by injuries, particularly to star Mexican striker Javier 'Chicharito' Hernandez.

"We understand where we're at, and we understand where we're going, and we also understand the context of the situation. You can't take context out of a story and just write a story, because that in itself is bullshit. Right?" he said.

But Vanney, who took Toronto FC from strugglers to the MLS title in 2017, also offered some home truths to those who remember the Galaxy, five times MLS champions, as the league's first powerhouse.

"There's now 29 teams in the league that are also trying to do the same thing. This is no longer a league of 12 teams or 19 teams of which the Galaxy is the spender... that's different than everybody else," he said.

"We're in a league with a lot of very ambitious clubs and teams and some that have are ahead of us in terms of making roster decisions (who) have settled their groups in.

"No problem. We're in the process of over the last years of rehauling and and resetting and building our group from inside out and working together as a team to build the club inside and out. And we're just working through the process," he said.

The good news for Vanney is that former Manchester United striker Hernandez should be back in the starting line-up in the derby, known as 'El Trafico', a playful reference to the California metropolis's notoriously gridlocked freeways and roads.

LAFC coach Steve Cherundolo has a very different problem to his counterpart, having to handle the demands of competing for the title and the latter stage of CONCACAF competition, but believes his team are coping well.

"I think that has to do with experience in the locker room. I think we have a lot of players who have done this before. That helps," he said.

The weekend's other West Coast derby sees struggling Portland Timbers, with one win from seven, host conference leaders Seattle Sounders.

New club St Louis City made a record-breaking start to the season as the first expansion club to win their opening five games but two straight losses have brought Bradley Cornell's team down to earth.

Unbeatan Cincinnati travel to St.Louis with the best record in the league with five wins and two draws.