Perceived as one of the big players in this summer's free agency, the Houston Rockets have made no secret about their desire for current Los Angeles Laker center Dwight Howard.

However, the Rockets do have a back-up plan, and may pursue injured Philadelphia 76ers big man Andrew Bynum, according to ESPN.

Once again, Howard and Bynum find themselves at the heart of NBA teams' struggle to land a franchise center. Both were the centerpieces in the biggest trade of last offseason, with Howard leaving the Orlando Magic and Bynum shipped out of L.A.

The Rockets were thought to be one of the teams chasing a Howard trade last year, but didn't have a desirable enough package to send back to Orlando.

Houston has about $39 million committed to salary next season, which leaves them plenty of room to make a pitch to Howard, a free agent at the end of the season. The three-time Defensive Player of the Year has fought through back and shoulder injuries this season, with his scoring and rebounding taking a significant hit.

Despite those setbacks, Howard, 27, is still considered the top center in the league and the summer. Under the new salary cap rules that will kick in next year, Howard can make upwards of $17 million a season. That's a bit of a hit for the big man, who is making $19.2 million this season.

Bynum hasn’t seen the court this season due to severe knee injuries that were reportedly re-aggravated after a night of bowling. According to USA Today, Bynum was planning on a return to the court sometime this month, but that was before injections he had in his knee didn’t work as well as he and the 76ers had hoped.

A healthy Bynum contributed to two Lakers championships, with his powerful build, polished post moves, and ability to control the paint. For his career, Bynum has averaged 11.7 points 7.8 rebounds and 1.6 blocks per game. His numbers are expected to increase by not playing with Kobe Bryant, who often is among the leaders in shots taken.

Los Angeles traded for Howard hoping a season on the left coast would convince him to sign a long-term maximum deal. The Lakers are currently 3.5 games back of Houston for the final playoff spot in the Western Conference, and Howard has missed three straight games with a torn labrum. Los Angeles reportedly told Howard they would not trade him, as it was rumored they were exploring such options rather than risk him leaving for nothing in return.

The 27-23 Rockets are on pace to make the playoffs for the first time since 2009, with guards Jeremy Lin and James Harden guiding the NBA’s second highest scoring offense. A big man like Howard or Bynum could place Houston amongst the elite in the West for the next half decade.

Houston almost landed L.A.'s other big man Pau Gasol, but that trade was nixed by NBA commissioner David Stern before last season. The same trade would have sent point guard Chris Paul to the Lakers.