[Tex/LaTex] Vertically align subfloats at the top while having subcaptions vertically aligned below the subfloats

Question

I have a float with two subfloats:

I want the circles to be vertically aligned from their top such as in the following figure. But I don't want the subcaptions to be placed above the subfloats but vertically aligned below as in the figure above.

I'm not bound to any package in particular (even if I used subfig for this examples). I have tried http://gicl.cs.drexel.edu/people/tjkopena/wiki/pmwiki.php?n=SWAT.VerticallyAligningSubfigures, http://www.howtotex.com/tips-tricks/vertical-alignment-of-subfigures/ and https://stackoverflow.com/questions/2328403/vertical-alignment-of-subfigures-latex without success.

\documentclass{article}

\usepackage{tikz}
\usepackage{subfig}

%\captionsetup[subfloat]{position=top}% Uncomment this to generate the second figure

\begin{document}

\begin{figure}
\centering
\subfloat[Small circle]{%
  \begin{tikzpicture}
    \draw circle (1.25cm) {};
  \end{tikzpicture}%
}
\qquad
\subfloat[Big circle]{%
  \begin{tikzpicture}
    \draw circle (2cm) {};
  \end{tikzpicture}%
}
\caption{Circles}
\end{figure}

\end{document}

Answer 1

As suggested by Mico in his answer it can be done with the floatrow package. To make subcaptions it depends on subcaption which depends on caption.

\documentclass{article}

\usepackage{tikz}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{floatrow}
\usepackage{calc}% To calculate width for \FBwidth

\floatsetup{ 
  heightadjust=object,
  valign=t
}

\begin{document}

\begin{figure}
\ffigbox
{%
  \begin{subfloatrow}
    \ffigbox[\FBwidth+0.5cm]% Width of subfloat
    {%
      \begin{tikzpicture}
        \draw circle (1.25cm) {};
      \end{tikzpicture}%
    }
    {%
      \subcaption{Small circle}%
    }
    \ffigbox[\FBwidth+0.5cm]% Width of subfloat
    {%
      \begin{tikzpicture}
        \draw circle (2cm) {};
      \end{tikzpicture}%
    }
    {%
      \subcaption{Big circle}%
    }
  \end{subfloatrow}
}
{%
  \caption{Circles}%
}
\end{figure}

\end{document}