Knicks big man Achiuwa out 2-4 weeks with strained hamstring

New York Knicks big man Precious Achiuwa has suffered a strained left hamstring and will be reevaluated in two to four weeks, the team announced Sunday.

It's unclear when Achiuwa, who has played in all five of the Knicks' preseason games, injured the hamstring.

The Knicks are already without center Mitchell Robinson to start the season as he rehabs from two ankle procedures over the past year. The Knicks are targeting January for a possible return date for Robinson, sources told ESPN's Shams Charania.

With center Isaiah Hartenstein departing in free agency, newly acquired Karl-Anthony Towns and Jericho Sims will be the only healthy centers on guaranteed deals left on New York's roster when they open the regular season Tuesday against the Boston Celtics .