SANTA CLARA, Calif. -- Given the seemingly never-ending spate of injuries that plague his team, San Francisco 49ers coach Kyle Shanahan long ago learned not to believe too much in what he's told on game days, whether the news is good or bad.

Shanahan prefers to wait for further tests to take place the next day, which is why he was able to breathe a small sigh of relief Monday when he was informed that quarterback Jimmy Garoppolo's right calf and left tackle Trent Williams' right shoulder aren't going to be long-term injuries.

According to Shanahan, Garoppolo and Williams will be evaluated as this week goes on and both have a chance to play Sunday against the Arizona Cardinals.

"At least we know that it's nothing too serious where it will be long term, which was a possibility," Shanahan said. "I think Trent, we got a little bit better news than Jimmy, but Jimmy, we've got to see how he reacts here in the next two days. But both of them were definitely better news today than the feeling we had last night."

The closer look at Garoppolo revealed a bruised calf, which could take some time to heal but might also be only a few days, which would allow Garoppolo to start against the Cardinals.

"It does mean he has a chance," Shanahan said. "It wasn't as bad as what we thought it might have been. He's in a lot of pain, still sore. Hopefully by the time he comes in Wednesday, if it's getting better, then he'll have a good chance. If it hasn't improved at all by Wednesday, it will probably be a little bit longer."

The news was even better for Williams. While Shanahan was less clear on what, exactly, the shoulder injury is, he did say Williams is dealing with some fluid in the shoulder that needs to clear up. Still, he was optimistic Williams will be OK for Arizona.

"That was some of probably the best news we got considering what we were worried about initially," Shanahan said. "There is some fluid in there and stuff so there are some issues with it, but that's something, hopefully, he can recover here before Sunday."

If neither Garoppolo nor Williams is able to return Sunday, they would both be positioned to play in the Niners' next game, which would come two weeks later on Oct. 24 after their Week 6 bye.

While Shanahan was hopeful about both players, he did mention that Garoppolo was a bit more questionable than Williams. Which means rookie Trey Lance, who played the second half in place of Garoppolo in Sunday's 28-21 loss to the Seattle Seahawks, could still make his first NFL start.

Garoppolo said he suffered the injury on San Francisco's first offensive series and indicated he thought a Seahawks defender has stepped on his calf. Garoppolo tried to play through the injury and made it to halftime before giving way to Lance.

Lance finished 9-of-18 for 157 yards with two touchdowns and ran seven times for 41 yards in Garoppolo's stead.

On Monday, Shanahan acknowledged that the uncertainty surrounding Garoppolo's status means the Niners will have to begin building a game plan that at least considers the possibility Lance will start in Arizona.

"Every week you want to tell him to approach it like he's the starting quarterback," Shanahan said. "This is the first week going into it that he has legitimately got a chance to on the first play. So, he's got to approach it that way, learn from the stuff he did last night and come in ready to go on Wednesday."

Elsewhere on the injury front, the 49ers will be without kicker Robbie Gould for three to five weeks. Gould suffered a groin strain just before the loss to Seattle and did not play. The 49ers are expected to work out kickers on Tuesday and sign one as they consider whether to put Gould on injured reserve.

Tight end George Kittle, who played through his own calf injury against the Seahawks after missing two practices last week, will have a similar approach in practice this week. Shanahan said Kittle will be managed throughout the week, as the Niners hope to have him available against the Cardinals.