MELBOURNE -- This is brutal.

The 49ers just lost starting defensive tackle Alfred Collins for the entire season with a torn patellar tendon he suffered on Tuesday (in Australia) during practice. The recovery time for this injury typically is 6 to 12 for most people, although it can be a career-ender for professional athletes. For what it's worth, former 49ers center Weston Richburg tore his patellar tendon in 2019 and never played again.

Granted, Collins is 24, while Richburg was 28 when he went down. So Collins might have a better chance to return to the field than Richburg had. But Collins also weighs more than 330 pounds. He might have to slim down to give his injured knee less weight to bear.

Collins was the 49ers' second-round draft pick last season, and while he started off his rookie season slow, he steadily improved and finished his rookie season as the best run defender who was still healthy on the defensive line. But this offseason, he had shoulder surgery to repair a torn labrum. And when he returned to practice during training camp, he never seemed quite right. He couldn't disengage from blockers, which means his shoulder might have still been an issue. And his conditioning wasn't good, which is why he played so poorly during the preseason.

So even before Collins injured his knee, the 49ers might have been looking for other options to start next to defensive tackle Osa Odighizuwa.

Here are the options: Second-year defensive tackle CJ West who had a rough training camp, undrafted rookie free agent James Thompson Jr. who had a good training camp but currently is injured, and rookie fourth-round pick Gracen Halton who made some nice plays during the preseason before injuring his ankle. He seems healthy now.

None of those options are great. I'm guessing the 49ers will go with West because he was a fourth-round pick last year and he has playing experience. Eventually, and maybe sooner rather than later, I expect Gracen Halton will take that job once he shows that he can play and stay healthy.

Keep in mind, Collins was not a "three-down player." He was a two-down player, meaning first and second down. On third down, he would come off the field and get replaced by a defensive end who would move over to defensive tackle. Early in the season, that player would be Keion White. In a few months, that player will be Mykel Williams.

So Collins' injury isn't necessarily a death blow to the 49ers' season, but it does make a thin position even thinner.