Britney Spears' constant ally was grilled by her ex Kevin Federline's attorney. Sam Lutfi, the pop stars' confidant and loyal companion, has endured questioning by Mark Kaplan Thursday morning regarding the ex-couple's ongoing custody battle.

E! News has quoted a source from the Spears camp saying, "Sam would never sell [Spears] out. There is no bigger supporter of Britney than Sam. I can't imagine Kaplan is going to get much out of him."

No word yet on what went on in the deposition.

Kaplan has already deposed several of Spears' pals, including Ali Sims, former manager Larry Rudolf and former bodyguard Daimon Shippen. Other members of Spears' camp are also in line for questioning.

Legal reps for both Spears and Federline will be back in court on February 4 for the next hearing schedule.

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