How do I insert a line break in an xtable caption?

Question

I'm sure it's a simple solution but Ive been searching all day trying to solve this. All I want to do is split an xtable caption over 2 lines. I've tried \n and caption.width to no avail.

\documentclass{article}

\usepackage{caption}

\begin{document}

<<makedata,echo=TRUE,results='asis'>>=
df <- matrix(round(rnorm(9, 20, 10)), 3, 3)
colnames(df) <- c("Column1","Column2","Column3")
require(xtable)
print (xtable(df, caption="Title1\nTitle2"),caption.placement="top")
@




\end{document} 

Answer 1

I think you need \\\\ so that it will print out in the tex file as \\ which creates a line break.

print (xtable(df, caption="Title1\\\\Title2"),caption.placement="top")

Answer 2

Sam's answer led me in the right direction, but I had to use \\newline instead of \\\\ since I was getting latex errors about overflowed boxes. Maybe the difference is that I'm generating my captions dynamically:

title <- paste("some text","\\newline",sep='')
print(xtable(df, caption=title))