POWER OF ATTORNEY

        KNOW ALL BY THESE PRESENTS, that the undersigned hereby makes,
constitutes and appoints Fan Yu, acting singly and with full power of
substitution or revocation, the undersigned's true and lawful attorney-in-fact,
with full power and authority as hereinafter described on behalf of and in the
name, place and stead of the undersigned to:

        (i)   execute for and on behalf of the undersigned, in the undersigned's
              capacity as a director, officer or beneficial owner of ordinary
              shares of ABG Acquisition Corp. I, a Cayman Islands exempted
              company (the "Company"), any Schedule 13D or Schedule 13G, and any
              amendments, supplements or exhibits thereto (including any joint
              filing agreements) required to be filed by the undersigned under
              Section 13 of the Securities Exchange Act of 1934, as amended, and
              the rules promulgated thereunder (the "Exchange Act"), and any
              Forms 3, 4, and 5 and any amendments, supplements or exhibits
              thereto required to be filed by the undersigned under Section
              16(a) of the Exchange Act;

        (ii)  do and perform any and all acts for and on behalf of the
              undersigned which may be necessary or desirable to complete and
              execute any such schedules or forms and timely file such forms
              with the United States Securities and Exchange Commission and any
              applicable stock exchange; and

        (iii) take any other action of any type whatsoever in connection with
              the foregoing which, in the opinion of such attorneys-in-fact, may
              be of benefit to, in the best interest of, or legally required by,
              the undersigned, it being understood that the documents executed
              by such attorney-in-fact on behalf of the undersigned pursuant to
              this Power of Attorney shall be in such form and shall contain
              such terms and conditions as such attorney-in-fact may approve in
              such attorney-in-fact's discretion.

        The undersigned hereby grants to such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact's substitute or
substitutes, shall lawfully do or cause to be done by virtue of this power of
attorney and the rights and powers herein granted. The undersigned acknowledges
that the foregoing attorney-in-fact, in serving in such capacity at the request
of the undersigned, are not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with, or any liability for the failure
to comply with, Section 13 and/or Section 16 of the Exchange Act.

        This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file reports or schedules under Section 13
or Section 16 of the Exchange Act with respect to the Company, unless earlier
revoked by the undersigned in a signed writing delivered to the foregoing
attorney-in-fact.

                                     *  *  *  *  *

        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 16th day of February 2021.

                                        By: /s/ Jean-Pierre Sommadossi
                                            ------------------------------------
                                        Name:  Jean-Pierre Sommadossi
                                        Title: Director