FRISCO, Texas – FC Dallas head coach Schellas Hyndman has utilized the same starting XI for four straight matches, but Jackson’s red card against the Vancouver Whitecaps last week assures the streak won’t reach five.

It's likely that won’t be the only change to the lineup, either.

George John and Andrew Jacobson were both held out of practice Monday and are unlikely to play against the Portland Timbers on Wednesday night (9 pm ET, watch on MLS Live). Jacobson tweaked a hamstring and John suffered a knee injury against the Whitecaps and, although x-rays and MRIs taken last week came back negative for both players, the team prefers to proceed slowly.

“The thing we have to consider is we’ve got only a few days before we play again and if we push A.J. and George too soon, then we may lose them for this game and then the next game and however many more games,” Hyndman explained to reporters on Monday, "so we have to be cautious."

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If John can’t go, center backs Stephen Keel and Walker Zimmerman are both cleared to play, according to Hyndman, but may not have the game fitness he’d like to see before giving either their first start of the season.

“That’s a difficult thing to do to be thrown right into it,” Hyndman said. “Is that better [using the more experienced player] or is it worse not knowing how he’s going to respond? Right now, I think it’s very difficult to throw new people out there.”

One possibility if Keel nor Zimmerman are ready to start might be moving Zach Lloyd to center back. This would give London Woodberry an opportunity at his more natural outside back (where Hyndman has said he prefers his young Homegrown signing) with either Keel or Zimmerman on the bench.

In the midfield, Fabián Castillo and Je-Vaughn Watson will be called upon to fill Jackson and Jacobson’s cleats.

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“If we don’t have A.J., then we may see both of them,” Hyndman revealed. “I thought they had a very good practice [Monday], but anytime you make one change, it affects everyone. That’s the thing we have to be concerned about right now. With Jackson out, you’ve got to change. If George is out, that will be another change. If A.J. is out, that will be another change. All of a sudden, you could have three or four changes.”

Castillo has started four matches this season and has appeared in every game this season. Watson has appeared in six matches, but has not started since the season opener. He told MLSsoccer.com that he’s very confident of his ability to help his team this week.

“They’re not really speedy, especially on the left side, so we can exploit a lot of space there," the Jamaican international said. "Either me or Castillo … can go and get behind them a couple of times when David [Ferreira] or Blas [Pérez] is playing through balls.”