PLYMOUTH Argyle continue to be plagued by injury problems as they prepare to tackle Westcountry rivals Bristol City in tonight's vital Coca-Cola Championship clash at Home Park.

The worst-case scenario could see the Pilgrims, who are in desperate need of victories to retain hope of avoiding relegation from the Championship, take on the Robins without three members of the back four they picked for last Saturday's 1-1 draw at Coventry City.

Central defender Kari Arnason and full-back Karl Duguid are both doubtful participants tonight, while full-back Richard Eckersley will not be able to play against the Ashton Gate outfit.

Argyle winger Craig Noone will miss his third match in a row, but there is some good news on the injury front for the struggling Pilgrims. Full-back Gary Sawyer, who took a knock on a shin on Saturday, is likely to be available tonight. So is central defender Réda Johnson, who has not yet played this month because of a groin injury.

Argyle head coach Paul Mariner is very keen to find and stick to a settled defence as he strives to pick a line-up capable of keeping clean- sheets, but he has been out of luck. The Pilgrims may have to field a patched-up defence tonight.

"It's crucial to have a settled back four, and we just can't get a settled back four," Mariner said yesterday. "Sawyer is available, I think, but Arnason is touch and go at the moment. He's going to have treatment today and tomorrow."

Arnason and Duguid both sustained calf knocks at Coventry on Saturday, and Arnason's injury is more severe than Duguid's. "Arnason's kick on the calf is worse than anybody else's," Mariner said. "It has sort of knotted up, which is always difficult.

"I think Duguid is going to be OK," the head coach added. "I think Réda Johnson will be available, which is good, but Eckersley is unavailable and so is Noone."

Eckersley failed to finish last Saturday's match, after suffering a groin strain. After sitting out two matches because of foot and shin damage, Noone returned to training yesterday.

It was not long before he was bothered by a separate injury, however. "Noone trained today, but he came out with a knee injury," Mariner explained. The winger has suffered from intermittent knee problems for much of the season.

Reinforcements have not yet arrived at Home Park. Central defender Bondz N'Gala has not concluded his proposed loan transfer from West Ham United, and did not train with the Pilgrims yesterday morning. Zimbabwe international full-back Onismor Bhasera is waiting to be granted a visa, and is unlikely to be part of Plymouth's squad before the end of the week.

"We're short in central defence," Mariner admitted, "and we're still trying to resolve the N'Gala situation." The 20-year-old Londoner was due to arrive at Home Park last Thursday, after the Pilgrims agreed a deal to borrow him from the Hammers, but the move has not yet taken place.

"I can't really tell you why it has dragged on for so long," Mariner added. "I wish we could get it resolved. If he was here, he would probably be starting, subject to Arnason's fitness tests. He was there at the game [at Coventry] on Saturday and I thought everything was finalised, but it isn't."

Bhasera is joining Plymouth as a free agent, but adding the 24- year-old to Argyle's staff has not been simple. The Pilgrims won an appeal to secure a UK work permit for the former Kaizer Chiefs left-back last week, but there is still some 'red tape' to cut through. "He isn't going to get his visa today, so he won't be available tomorrow," Mariner said. "It isn't an ideal scenario, but we'll get on with it."

Argyle took a look at three trialists on their training ground yesterday, but the trio are not potential signings for use this season. Instead, they are possible candidates for contracts in the summer, according to Mariner.